subroutine circle_unit_van_der_corput ( x ) !*****************************************************************************80 ! !! CIRCLE_UNIT_VAN_DER_CORPUT picks a van der Corput point on the unit circle. ! ! Discussion: ! ! This routine computes the "next" van der Corput number U, converts it ! to an angle between 0 and 2 PI, and determines the corresponding ! X and Y coordinates on the circle. ! ! You can get or set the van der Corput seed, which determines the next ! value, by calling VAN_DER_CORPUT_SEED_GET or VAN_DER_CORPUT_SEED_SET. ! ! Licensing: ! ! This code is distributed under the GNU LGPL license. ! ! Modified: ! ! 10 March 2003 ! ! Author: ! ! John Burkardt ! ! Parameters: ! ! Output, real ( kind = 8 ) X(2), the next van der Corput point ! on the circle. ! implicit none real ( kind = 8 ) angle real ( kind = 8 ), parameter :: pi = 3.141592653589793D+00 real ( kind = 8 ) u real ( kind = 8 ) x(2) call van_der_corput ( u ) angle = 2.0D+00 * pi * u x(1) = cos ( angle ) x(2) = sin ( angle ) return end subroutine get_seed ( seed ) !*****************************************************************************80 ! !! GET_SEED returns a seed for the random number generator. ! ! Discussion: ! ! The seed depends on the current time, and ought to be (slightly) ! different every millisecond. Once the seed is obtained, a random ! number generator should be called a few times to further process ! the seed. ! ! Licensing: ! ! This code is distributed under the GNU LGPL license. ! ! Modified: ! ! 02 August 2004 ! ! Author: ! ! John Burkardt ! ! Parameters: ! ! Output, integer ( kind = 4 ) SEED, a pseudorandom seed value. ! implicit none integer ( kind = 4 ), parameter :: i4_huge = 2147483647 integer ( kind = 4 ) seed real ( kind = 8 ) temp character ( len = 10 ) time character ( len = 8 ) today integer ( kind = 4 ) values(8) character ( len = 5 ) zone call date_and_time ( today, time, zone, values ) temp = 0.0D+00 temp = temp + real ( values(2) - 1, kind = 8 ) / 11.0D+00 temp = temp + real ( values(3) - 1, kind = 8 ) / 30.0D+00 temp = temp + real ( values(5), kind = 8 ) / 23.0D+00 temp = temp + real ( values(6), kind = 8 ) / 59.0D+00 temp = temp + real ( values(7), kind = 8 ) / 59.0D+00 temp = temp + real ( values(8), kind = 8 ) / 999.0D+00 temp = temp / 6.0D+00 do while ( temp <= 0.0D+00 ) temp = temp + 1.0D+00 end do do while ( 1.0D+00 < temp ) temp = temp - 1.0D+00 end do seed = int ( real ( i4_huge, kind = 8 ) * temp ) ! ! Never use a seed of 0 or maximum integer. ! if ( seed == 0 ) then seed = 1 end if if ( seed == i4_huge ) then seed = seed - 1 end if return end subroutine get_unit ( iunit ) !*****************************************************************************80 ! !! GET_UNIT returns a free FORTRAN unit number. ! ! Discussion: ! ! A "free" FORTRAN unit number is an integer between 1 and 99 which ! is not currently associated with an I/O device. A free FORTRAN unit ! number is needed in order to open a file with the OPEN command. ! ! If IUNIT = 0, then no free FORTRAN unit could be found, although ! all 99 units were checked (except for units 5, 6 and 9, which ! are commonly reserved for console I/O). ! ! Otherwise, IUNIT is an integer between 1 and 99, representing a ! free FORTRAN unit. Note that GET_UNIT assumes that units 5 and 6 ! are special, and will never return those values. ! ! Licensing: ! ! This code is distributed under the GNU LGPL license. ! ! Modified: ! ! 26 October 2008 ! ! Author: ! ! John Burkardt ! ! Parameters: ! ! Output, integer ( kind = 4 ) IUNIT, the free unit number. ! implicit none integer ( kind = 4 ) i integer ( kind = 4 ) ios integer ( kind = 4 ) iunit logical lopen iunit = 0 do i = 1, 99 if ( i /= 5 .and. i /= 6 .and. i /= 9 ) then inquire ( unit = i, opened = lopen, iostat = ios ) if ( ios == 0 ) then if ( .not. lopen ) then iunit = i return end if end if end if end do return end function i4_log_2 ( i ) !*****************************************************************************80 ! !! I4_LOG_2 returns the integer part of the logarithm base 2 of an I4. ! ! Discussion: ! ! For positive I4_LOG_2(I), it should be true that ! 2**I4_LOG_2(X) <= |I| < 2**(I4_LOG_2(I)+1). ! The special case of I4_LOG_2(0) returns -HUGE(). ! ! An I4 is an integer ( kind = 4 ) value. ! ! Example: ! ! I I4_LOG_2 ! ! 0 -1 ! 1, 0 ! 2, 1 ! 3, 1 ! 4, 2 ! 5, 2 ! 6, 2 ! 7, 2 ! 8, 3 ! 9, 3 ! 10, 3 ! 127, 6 ! 128, 7 ! 129, 7 ! ! Licensing: ! ! This code is distributed under the GNU LGPL license. ! ! Modified: ! ! 13 January 2003 ! ! Author: ! ! John Burkardt ! ! Parameters: ! ! Input, integer ( kind = 4 ) I, the number whose logarithm base 2 ! is desired. ! ! Output, integer ( kind = 4 ) I4_LOG_2, the integer part of the ! logarithm base 2 of the absolute value of I. ! implicit none integer ( kind = 4 ) i integer ( kind = 4 ) i_abs integer ( kind = 4 ) i4_log_2 integer ( kind = 4 ), parameter :: i4_huge = 2147483647 if ( i == 0 ) then i4_log_2 = - i4_huge else i4_log_2 = 0 i_abs = abs ( i ) do while ( 2 <= i_abs ) i_abs = i_abs / 2 i4_log_2 = i4_log_2 + 1 end do end if return end subroutine i4_to_van_der_corput ( seed, base, r ) !*****************************************************************************80 ! !! I4_TO_VAN_DER_CORPUT computes an element of a van der Corput sequence. ! ! Discussion: ! ! The van der Corput sequence is often used to generate a "subrandom" ! sequence of points which have a better covering property ! than pseudorandom points. ! ! The van der Corput sequence generates a sequence of points in [0,1] ! which (theoretically) never repeats. Except for SEED = 0, the ! elements of the van der Corput sequence are strictly between 0 and 1. ! ! The van der Corput sequence writes an integer in a given base B, ! and then its digits are "reflected" about the decimal point. ! This maps the numbers from 1 to N into a set of numbers in [0,1], ! which are especially nicely distributed if N is one less ! than a power of the base. ! ! Hammersley suggested generating a set of N nicely distributed ! points in two dimensions by setting the first component of the ! Ith point to I/N, and the second to the van der Corput ! value of I in base 2. ! ! Halton suggested that in many cases, you might not know the number ! of points you were generating, so Hammersley's formulation was ! not ideal. Instead, he suggested that to generate a nicely ! distributed sequence of points in M dimensions, you simply ! choose the first M primes, P(1:M), and then for the J-th component of ! the I-th point in the sequence, you compute the van der Corput ! value of I in base P(J). ! ! Thus, to generate a Halton sequence in a 2 dimensional space, ! it is typical practice to generate a pair of van der Corput sequences, ! the first with prime base 2, the second with prime base 3. ! Similarly, by using the first K primes, a suitable sequence ! in K-dimensional space can be generated. ! ! The generation is quite simple. Given an integer SEED, the expansion ! of SEED in base BASE is generated. Then, essentially, the result R ! is generated by writing a decimal point followed by the digits of ! the expansion of SEED, in reverse order. This decimal value is actually ! still in base BASE, so it must be properly interpreted to generate ! a usable value. ! ! Example: ! ! BASE = 2 ! ! SEED SEED van der Corput ! decimal binary binary decimal ! ------- ------ ------ ------- ! 0 = 0 => .0 = 0.0 ! 1 = 1 => .1 = 0.5 ! 2 = 10 => .01 = 0.25 ! 3 = 11 => .11 = 0.75 ! 4 = 100 => .001 = 0.125 ! 5 = 101 => .101 = 0.625 ! 6 = 110 => .011 = 0.375 ! 7 = 111 => .111 = 0.875 ! 8 = 1000 => .0001 = 0.0625 ! ! Licensing: ! ! This code is distributed under the GNU LGPL license. ! ! Modified: ! ! 18 December 2002 ! ! Author: ! ! John Burkardt ! ! Reference: ! ! John Halton, ! On the efficiency of certain quasi-random sequences of points ! in evaluating multi-dimensional integrals, ! Numerische Mathematik, ! Volume 2, pages 84-90, 1960. ! ! John Hammersley, ! Monte Carlo methods for solving multivariable problems, ! Proceedings of the New York Academy of Science, ! Volume 86, pages 844-874, 1960. ! ! Johannes van der Corput, ! Verteilungsfunktionen I & II, ! Nederl. Akad. Wetensch. Proc., ! Volume 38, 1935, pages 813-820, pages 1058-1066. ! ! Parameters: ! ! Input, integer ( kind = 4 ) SEED, the seed or index of the desired element. ! SEED should be nonnegative. ! SEED = 0 is allowed, and returns R = 0. ! ! Input, integer ( kind = 4 ) BASE, the van der Corput base, which is ! typically a prime number. BASE must be greater than 1. ! ! Output, real ( kind = 8 ) R, the SEED-th element of the van der ! Corput sequence for base BASE. ! implicit none integer ( kind = 4 ) base real ( kind = 8 ) base_inv integer ( kind = 4 ) digit real ( kind = 8 ) r integer ( kind = 4 ) seed integer ( kind = 4 ) seed2 if ( base <= 1 ) then write ( *, '(a)' ) ' ' write ( *, '(a)' ) 'I4_TO_VAN_DER_CORPUT - Fatal error!' write ( *, '(a)' ) ' The input base BASE is <= 1!' write ( *, '(a,i6)' ) ' BASE = ', base stop 1 end if if ( seed < 0 ) then write ( *, '(a)' ) ' ' write ( *, '(a)' ) 'I4_TO_VAN_DER_CORPUT - Fatal error!' write ( *, '(a)' ) ' The input base SEED is < 0!' write ( *, '(a,i6)' ) ' SEED = ', seed stop 1 end if seed2 = seed r = 0.0D+00 base_inv = 1.0D+00 / real ( base, kind = 8 ) do while ( seed2 /= 0 ) digit = mod ( seed2, base ) r = r + real ( digit, kind = 8 ) * base_inv base_inv = base_inv / real ( base, kind = 8 ) seed2 = seed2 / base end do return end subroutine i4_to_van_der_corput_sequence ( seed, base, n, r ) !*****************************************************************************80 ! !! I4_TO_VAN_DER_CORPUT_SEQUENCE: next N elements of a van der Corput sequence. ! ! Licensing: ! ! This code is distributed under the GNU LGPL license. ! ! Modified: ! ! 28 June 2004 ! ! Author: ! ! John Burkardt ! ! Reference: ! ! John Halton, ! On the efficiency of certain quasi-random sequences of points ! in evaluating multi-dimensional integrals, ! Numerische Mathematik, ! Volume 2, pages 84-90, 1960. ! ! Johnannes van der Corput, ! Verteilungsfunktionen I & II, ! Nederl. Akad. Wetensch. Proc., ! Volume 38, 1935, pages 813-820, pages 1058-1066. ! ! Parameters: ! ! Input, integer ( kind = 4 ) SEED, the seed or index of the desired element. ! SEED should be nonnegative. ! SEED = 0 is allowed, and returns R = 0. ! ! Input, integer ( kind = 4 ) BASE, the van der Corput base, which is ! typically a prime number. BASE must be greater than 1. ! ! Input, integer ( kind = 4 ) N, the number of elements desired. ! ! Output, real ( kind = 8 ) R(N), the SEED-th through (SEED+N-1)-th ! elements of the van der Corput sequence for base BASE. ! implicit none integer ( kind = 4 ) n integer ( kind = 4 ) base real ( kind = 8 ) base_inv integer ( kind = 4 ) digit(n) real ( kind = 8 ) r(n) integer ( kind = 4 ) seed integer ( kind = 4 ) seed2(n) if ( base <= 1 ) then write ( *, '(a)' ) ' ' write ( *, '(a)' ) 'I4_TO_VAN_DER_CORPUT_SEQUENCE - Fatal error!' write ( *, '(a)' ) ' The input base BASE is <= 1!' write ( *, '(a,i6)' ) ' BASE = ', base stop 1 end if if ( seed < 0 ) then write ( *, '(a)' ) ' ' write ( *, '(a)' ) 'I4_TO_VAN_DER_CORPUT_SEQUENCE - Fatal error!' write ( *, '(a)' ) ' The input base SEED is < 0!' write ( *, '(a,i6)' ) ' SEED = ', seed stop 1 end if ! ! Set SEED2 = (/ SEED, SEED+1, SEED+2, ..., SEED+N-1 /) ! call i4vec_indicator ( n, seed2 ) seed2(1:n) = seed2(1:n) + seed - 1 base_inv = 1.0D+00 / real ( base, kind = 8 ) r(1:n) = 0.0D+00 do while ( any ( seed2(1:n) /= 0 ) ) digit(1:n) = mod ( seed2(1:n), base ) r(1:n) = r(1:n) + real ( digit(1:n), kind = 8 ) * base_inv base_inv = base_inv / real ( base, kind = 8 ) seed2(1:n) = seed2(1:n) / base end do return end subroutine i4vec_indicator ( n, a ) !*****************************************************************************80 ! !! I4VEC_INDICATOR sets an I4VEC to the indicator vector A(I)=I. ! ! Licensing: ! ! This code is distributed under the GNU LGPL license. ! ! Modified: ! ! 09 November 2000 ! ! Author: ! ! John Burkardt ! ! Parameters: ! ! Input, integer ( kind = 4 ) N, the number of elements of A. ! ! Output, integer ( kind = 4 ) A(N), the array to be initialized. ! implicit none integer ( kind = 4 ) n integer ( kind = 4 ) a(n) integer ( kind = 4 ) i do i = 1, n a(i) = i end do return end function prime ( n ) !*****************************************************************************80 ! !! PRIME returns any of the first PRIME_MAX prime numbers. ! ! Discussion: ! ! PRIME_MAX is 1600, and the largest prime stored is 13499. ! ! Thanks to Bart Vandewoestyne for pointing out a typo, 18 February 2005. ! ! Licensing: ! ! This code is distributed under the GNU LGPL license. ! ! Modified: ! ! 18 February 2005 ! ! Author: ! ! John Burkardt ! ! Reference: ! ! Milton Abramowitz and Irene Stegun, ! Handbook of Mathematical Functions, ! US Department of Commerce, 1964, pages 870-873. ! ! Daniel Zwillinger, ! CRC Standard Mathematical Tables and Formulae, ! 30th Edition, ! CRC Press, 1996, pages 95-98. ! ! Parameters: ! ! Input, integer ( kind = 4 ) N, the index of the desired prime number. ! In general, is should be true that 0 <= N <= PRIME_MAX. ! N = -1 returns PRIME_MAX, the index of the largest prime available. ! N = 0 is legal, returning PRIME = 1. ! ! Output, integer ( kind = 4 ) PRIME, the N-th prime. If N is out of range, ! PRIME is returned as -1. ! implicit none integer ( kind = 4 ), parameter :: prime_max = 1600 integer ( kind = 4 ), save :: icall = 0 integer ( kind = 4 ) n integer ( kind = 4 ), save, dimension ( prime_max ) :: npvec integer ( kind = 4 ) prime if ( icall == 0 ) then icall = 1 npvec(1:100) = (/ & 2, 3, 5, 7, 11, 13, 17, 19, 23, 29, & 31, 37, 41, 43, 47, 53, 59, 61, 67, 71, & 73, 79, 83, 89, 97, 101, 103, 107, 109, 113, & 127, 131, 137, 139, 149, 151, 157, 163, 167, 173, & 179, 181, 191, 193, 197, 199, 211, 223, 227, 229, & 233, 239, 241, 251, 257, 263, 269, 271, 277, 281, & 283, 293, 307, 311, 313, 317, 331, 337, 347, 349, & 353, 359, 367, 373, 379, 383, 389, 397, 401, 409, & 419, 421, 431, 433, 439, 443, 449, 457, 461, 463, & 467, 479, 487, 491, 499, 503, 509, 521, 523, 541 /) npvec(101:200) = (/ & 547, 557, 563, 569, 571, 577, 587, 593, 599, 601, & 607, 613, 617, 619, 631, 641, 643, 647, 653, 659, & 661, 673, 677, 683, 691, 701, 709, 719, 727, 733, & 739, 743, 751, 757, 761, 769, 773, 787, 797, 809, & 811, 821, 823, 827, 829, 839, 853, 857, 859, 863, & 877, 881, 883, 887, 907, 911, 919, 929, 937, 941, & 947, 953, 967, 971, 977, 983, 991, 997, 1009, 1013, & 1019, 1021, 1031, 1033, 1039, 1049, 1051, 1061, 1063, 1069, & 1087, 1091, 1093, 1097, 1103, 1109, 1117, 1123, 1129, 1151, & 1153, 1163, 1171, 1181, 1187, 1193, 1201, 1213, 1217, 1223 /) npvec(201:300) = (/ & 1229, 1231, 1237, 1249, 1259, 1277, 1279, 1283, 1289, 1291, & 1297, 1301, 1303, 1307, 1319, 1321, 1327, 1361, 1367, 1373, & 1381, 1399, 1409, 1423, 1427, 1429, 1433, 1439, 1447, 1451, & 1453, 1459, 1471, 1481, 1483, 1487, 1489, 1493, 1499, 1511, & 1523, 1531, 1543, 1549, 1553, 1559, 1567, 1571, 1579, 1583, & 1597, 1601, 1607, 1609, 1613, 1619, 1621, 1627, 1637, 1657, & 1663, 1667, 1669, 1693, 1697, 1699, 1709, 1721, 1723, 1733, & 1741, 1747, 1753, 1759, 1777, 1783, 1787, 1789, 1801, 1811, & 1823, 1831, 1847, 1861, 1867, 1871, 1873, 1877, 1879, 1889, & 1901, 1907, 1913, 1931, 1933, 1949, 1951, 1973, 1979, 1987 /) npvec(301:400) = (/ & 1993, 1997, 1999, 2003, 2011, 2017, 2027, 2029, 2039, 2053, & 2063, 2069, 2081, 2083, 2087, 2089, 2099, 2111, 2113, 2129, & 2131, 2137, 2141, 2143, 2153, 2161, 2179, 2203, 2207, 2213, & 2221, 2237, 2239, 2243, 2251, 2267, 2269, 2273, 2281, 2287, & 2293, 2297, 2309, 2311, 2333, 2339, 2341, 2347, 2351, 2357, & 2371, 2377, 2381, 2383, 2389, 2393, 2399, 2411, 2417, 2423, & 2437, 2441, 2447, 2459, 2467, 2473, 2477, 2503, 2521, 2531, & 2539, 2543, 2549, 2551, 2557, 2579, 2591, 2593, 2609, 2617, & 2621, 2633, 2647, 2657, 2659, 2663, 2671, 2677, 2683, 2687, & 2689, 2693, 2699, 2707, 2711, 2713, 2719, 2729, 2731, 2741 /) npvec(401:500) = (/ & 2749, 2753, 2767, 2777, 2789, 2791, 2797, 2801, 2803, 2819, & 2833, 2837, 2843, 2851, 2857, 2861, 2879, 2887, 2897, 2903, & 2909, 2917, 2927, 2939, 2953, 2957, 2963, 2969, 2971, 2999, & 3001, 3011, 3019, 3023, 3037, 3041, 3049, 3061, 3067, 3079, & 3083, 3089, 3109, 3119, 3121, 3137, 3163, 3167, 3169, 3181, & 3187, 3191, 3203, 3209, 3217, 3221, 3229, 3251, 3253, 3257, & 3259, 3271, 3299, 3301, 3307, 3313, 3319, 3323, 3329, 3331, & 3343, 3347, 3359, 3361, 3371, 3373, 3389, 3391, 3407, 3413, & 3433, 3449, 3457, 3461, 3463, 3467, 3469, 3491, 3499, 3511, & 3517, 3527, 3529, 3533, 3539, 3541, 3547, 3557, 3559, 3571 /) npvec(501:600) = (/ & 3581, 3583, 3593, 3607, 3613, 3617, 3623, 3631, 3637, 3643, & 3659, 3671, 3673, 3677, 3691, 3697, 3701, 3709, 3719, 3727, & 3733, 3739, 3761, 3767, 3769, 3779, 3793, 3797, 3803, 3821, & 3823, 3833, 3847, 3851, 3853, 3863, 3877, 3881, 3889, 3907, & 3911, 3917, 3919, 3923, 3929, 3931, 3943, 3947, 3967, 3989, & 4001, 4003, 4007, 4013, 4019, 4021, 4027, 4049, 4051, 4057, & 4073, 4079, 4091, 4093, 4099, 4111, 4127, 4129, 4133, 4139, & 4153, 4157, 4159, 4177, 4201, 4211, 4217, 4219, 4229, 4231, & 4241, 4243, 4253, 4259, 4261, 4271, 4273, 4283, 4289, 4297, & 4327, 4337, 4339, 4349, 4357, 4363, 4373, 4391, 4397, 4409 /) npvec(601:700) = (/ & 4421, 4423, 4441, 4447, 4451, 4457, 4463, 4481, 4483, 4493, & 4507, 4513, 4517, 4519, 4523, 4547, 4549, 4561, 4567, 4583, & 4591, 4597, 4603, 4621, 4637, 4639, 4643, 4649, 4651, 4657, & 4663, 4673, 4679, 4691, 4703, 4721, 4723, 4729, 4733, 4751, & 4759, 4783, 4787, 4789, 4793, 4799, 4801, 4813, 4817, 4831, & 4861, 4871, 4877, 4889, 4903, 4909, 4919, 4931, 4933, 4937, & 4943, 4951, 4957, 4967, 4969, 4973, 4987, 4993, 4999, 5003, & 5009, 5011, 5021, 5023, 5039, 5051, 5059, 5077, 5081, 5087, & 5099, 5101, 5107, 5113, 5119, 5147, 5153, 5167, 5171, 5179, & 5189, 5197, 5209, 5227, 5231, 5233, 5237, 5261, 5273, 5279 /) npvec(701:800) = (/ & 5281, 5297, 5303, 5309, 5323, 5333, 5347, 5351, 5381, 5387, & 5393, 5399, 5407, 5413, 5417, 5419, 5431, 5437, 5441, 5443, & 5449, 5471, 5477, 5479, 5483, 5501, 5503, 5507, 5519, 5521, & 5527, 5531, 5557, 5563, 5569, 5573, 5581, 5591, 5623, 5639, & 5641, 5647, 5651, 5653, 5657, 5659, 5669, 5683, 5689, 5693, & 5701, 5711, 5717, 5737, 5741, 5743, 5749, 5779, 5783, 5791, & 5801, 5807, 5813, 5821, 5827, 5839, 5843, 5849, 5851, 5857, & 5861, 5867, 5869, 5879, 5881, 5897, 5903, 5923, 5927, 5939, & 5953, 5981, 5987, 6007, 6011, 6029, 6037, 6043, 6047, 6053, & 6067, 6073, 6079, 6089, 6091, 6101, 6113, 6121, 6131, 6133 /) npvec(801:900) = (/ & 6143, 6151, 6163, 6173, 6197, 6199, 6203, 6211, 6217, 6221, & 6229, 6247, 6257, 6263, 6269, 6271, 6277, 6287, 6299, 6301, & 6311, 6317, 6323, 6329, 6337, 6343, 6353, 6359, 6361, 6367, & 6373, 6379, 6389, 6397, 6421, 6427, 6449, 6451, 6469, 6473, & 6481, 6491, 6521, 6529, 6547, 6551, 6553, 6563, 6569, 6571, & 6577, 6581, 6599, 6607, 6619, 6637, 6653, 6659, 6661, 6673, & 6679, 6689, 6691, 6701, 6703, 6709, 6719, 6733, 6737, 6761, & 6763, 6779, 6781, 6791, 6793, 6803, 6823, 6827, 6829, 6833, & 6841, 6857, 6863, 6869, 6871, 6883, 6899, 6907, 6911, 6917, & 6947, 6949, 6959, 6961, 6967, 6971, 6977, 6983, 6991, 6997 /) npvec(901:1000) = (/ & 7001, 7013, 7019, 7027, 7039, 7043, 7057, 7069, 7079, 7103, & 7109, 7121, 7127, 7129, 7151, 7159, 7177, 7187, 7193, 7207, & 7211, 7213, 7219, 7229, 7237, 7243, 7247, 7253, 7283, 7297, & 7307, 7309, 7321, 7331, 7333, 7349, 7351, 7369, 7393, 7411, & 7417, 7433, 7451, 7457, 7459, 7477, 7481, 7487, 7489, 7499, & 7507, 7517, 7523, 7529, 7537, 7541, 7547, 7549, 7559, 7561, & 7573, 7577, 7583, 7589, 7591, 7603, 7607, 7621, 7639, 7643, & 7649, 7669, 7673, 7681, 7687, 7691, 7699, 7703, 7717, 7723, & 7727, 7741, 7753, 7757, 7759, 7789, 7793, 7817, 7823, 7829, & 7841, 7853, 7867, 7873, 7877, 7879, 7883, 7901, 7907, 7919 /) npvec(1001:1100) = (/ & 7927, 7933, 7937, 7949, 7951, 7963, 7993, 8009, 8011, 8017, & 8039, 8053, 8059, 8069, 8081, 8087, 8089, 8093, 8101, 8111, & 8117, 8123, 8147, 8161, 8167, 8171, 8179, 8191, 8209, 8219, & 8221, 8231, 8233, 8237, 8243, 8263, 8269, 8273, 8287, 8291, & 8293, 8297, 8311, 8317, 8329, 8353, 8363, 8369, 8377, 8387, & 8389, 8419, 8423, 8429, 8431, 8443, 8447, 8461, 8467, 8501, & 8513, 8521, 8527, 8537, 8539, 8543, 8563, 8573, 8581, 8597, & 8599, 8609, 8623, 8627, 8629, 8641, 8647, 8663, 8669, 8677, & 8681, 8689, 8693, 8699, 8707, 8713, 8719, 8731, 8737, 8741, & 8747, 8753, 8761, 8779, 8783, 8803, 8807, 8819, 8821, 8831 /) npvec(1101:1200) = (/ & 8837, 8839, 8849, 8861, 8863, 8867, 8887, 8893, 8923, 8929, & 8933, 8941, 8951, 8963, 8969, 8971, 8999, 9001, 9007, 9011, & 9013, 9029, 9041, 9043, 9049, 9059, 9067, 9091, 9103, 9109, & 9127, 9133, 9137, 9151, 9157, 9161, 9173, 9181, 9187, 9199, & 9203, 9209, 9221, 9227, 9239, 9241, 9257, 9277, 9281, 9283, & 9293, 9311, 9319, 9323, 9337, 9341, 9343, 9349, 9371, 9377, & 9391, 9397, 9403, 9413, 9419, 9421, 9431, 9433, 9437, 9439, & 9461, 9463, 9467, 9473, 9479, 9491, 9497, 9511, 9521, 9533, & 9539, 9547, 9551, 9587, 9601, 9613, 9619, 9623, 9629, 9631, & 9643, 9649, 9661, 9677, 9679, 9689, 9697, 9719, 9721, 9733 /) npvec(1201:1300) = (/ & 9739, 9743, 9749, 9767, 9769, 9781, 9787, 9791, 9803, 9811, & 9817, 9829, 9833, 9839, 9851, 9857, 9859, 9871, 9883, 9887, & 9901, 9907, 9923, 9929, 9931, 9941, 9949, 9967, 9973,10007, & 10009,10037,10039,10061,10067,10069,10079,10091,10093,10099, & 10103,10111,10133,10139,10141,10151,10159,10163,10169,10177, & 10181,10193,10211,10223,10243,10247,10253,10259,10267,10271, & 10273,10289,10301,10303,10313,10321,10331,10333,10337,10343, & 10357,10369,10391,10399,10427,10429,10433,10453,10457,10459, & 10463,10477,10487,10499,10501,10513,10529,10531,10559,10567, & 10589,10597,10601,10607,10613,10627,10631,10639,10651,10657 /) npvec(1301:1400) = (/ & 10663,10667,10687,10691,10709,10711,10723,10729,10733,10739, & 10753,10771,10781,10789,10799,10831,10837,10847,10853,10859, & 10861,10867,10883,10889,10891,10903,10909,10937,10939,10949, & 10957,10973,10979,10987,10993,11003,11027,11047,11057,11059, & 11069,11071,11083,11087,11093,11113,11117,11119,11131,11149, & 11159,11161,11171,11173,11177,11197,11213,11239,11243,11251, & 11257,11261,11273,11279,11287,11299,11311,11317,11321,11329, & 11351,11353,11369,11383,11393,11399,11411,11423,11437,11443, & 11447,11467,11471,11483,11489,11491,11497,11503,11519,11527, & 11549,11551,11579,11587,11593,11597,11617,11621,11633,11657 /) npvec(1401:1500) = (/ & 11677,11681,11689,11699,11701,11717,11719,11731,11743,11777, & 11779,11783,11789,11801,11807,11813,11821,11827,11831,11833, & 11839,11863,11867,11887,11897,11903,11909,11923,11927,11933, & 11939,11941,11953,11959,11969,11971,11981,11987,12007,12011, & 12037,12041,12043,12049,12071,12073,12097,12101,12107,12109, & 12113,12119,12143,12149,12157,12161,12163,12197,12203,12211, & 12227,12239,12241,12251,12253,12263,12269,12277,12281,12289, & 12301,12323,12329,12343,12347,12373,12377,12379,12391,12401, & 12409,12413,12421,12433,12437,12451,12457,12473,12479,12487, & 12491,12497,12503,12511,12517,12527,12539,12541,12547,12553 /) npvec(1501:1600) = (/ & 12569,12577,12583,12589,12601,12611,12613,12619,12637,12641, & 12647,12653,12659,12671,12689,12697,12703,12713,12721,12739, & 12743,12757,12763,12781,12791,12799,12809,12821,12823,12829, & 12841,12853,12889,12893,12899,12907,12911,12917,12919,12923, & 12941,12953,12959,12967,12973,12979,12983,13001,13003,13007, & 13009,13033,13037,13043,13049,13063,13093,13099,13103,13109, & 13121,13127,13147,13151,13159,13163,13171,13177,13183,13187, & 13217,13219,13229,13241,13249,13259,13267,13291,13297,13309, & 13313,13327,13331,13337,13339,13367,13381,13397,13399,13411, & 13417,13421,13441,13451,13457,13463,13469,13477,13487,13499 /) end if if ( n == -1 ) then prime = prime_max else if ( n == 0 ) then prime = 1 else if ( n <= prime_max ) then prime = npvec(n) else prime = -1 write ( *, '(a)' ) ' ' write ( *, '(a)' ) 'PRIME - Fatal error!' write ( *, '(a,i6)' ) ' Illegal prime index N = ', n write ( *, '(a,i6)' ) ' N should be between 1 and PRIME_MAX =', prime_max stop 1 end if return end subroutine r8mat_write ( output_filename, m, n, table ) !*****************************************************************************80 ! !! R8MAT_WRITE writes an R8MAT file. ! ! Discussion: ! ! An R8MAT is an array of R8 values. ! ! Licensing: ! ! This code is distributed under the GNU LGPL license. ! ! Modified: ! ! 31 May 2009 ! ! Author: ! ! John Burkardt ! ! Parameters: ! ! Input, character ( len = * ) OUTPUT_FILENAME, the output file name. ! ! Input, integer ( kind = 4 ) M, the spatial dimension. ! ! Input, integer ( kind = 4 ) N, the number of points. ! ! Input, real ( kind = 8 ) TABLE(M,N), the table data. ! implicit none integer ( kind = 4 ) m integer ( kind = 4 ) n integer ( kind = 4 ) j character ( len = * ) output_filename integer ( kind = 4 ) output_status integer ( kind = 4 ) output_unit character ( len = 30 ) string real ( kind = 8 ) table(m,n) ! ! Open the file. ! call get_unit ( output_unit ) open ( unit = output_unit, file = output_filename, & status = 'replace', iostat = output_status ) if ( output_status /= 0 ) then write ( *, '(a)' ) ' ' write ( *, '(a)' ) 'R8MAT_WRITE - Fatal error!' write ( *, '(a,i8)' ) ' Could not open the output file "' // & trim ( output_filename ) // '" on unit ', output_unit output_unit = -1 stop 1 end if ! ! Create a format string. ! ! For less precision in the output file, try: ! ! '(', m, 'g', 14, '.', 6, ')' ! if ( 0 < m .and. 0 < n ) then write ( string, '(a1,i8,a1,i8,a1,i8,a1)' ) '(', m, 'g', 24, '.', 16, ')' ! ! Write the data. ! do j = 1, n write ( output_unit, string ) table(1:m,j) end do end if ! ! Close the file. ! close ( unit = output_unit ) return end subroutine timestamp ( ) !*****************************************************************************80 ! !! TIMESTAMP prints the current YMDHMS date as a time stamp. ! ! Example: ! ! 31 May 2001 9:45:54.872 AM ! ! Licensing: ! ! This code is distributed under the GNU LGPL license. ! ! Modified: ! ! 18 May 2013 ! ! Author: ! ! John Burkardt ! ! Parameters: ! ! None ! implicit none character ( len = 8 ) ampm integer ( kind = 4 ) d integer ( kind = 4 ) h integer ( kind = 4 ) m integer ( kind = 4 ) mm character ( len = 9 ), parameter, dimension(12) :: month = (/ & 'January ', 'February ', 'March ', 'April ', & 'May ', 'June ', 'July ', 'August ', & 'September', 'October ', 'November ', 'December ' /) integer ( kind = 4 ) n integer ( kind = 4 ) s integer ( kind = 4 ) values(8) integer ( kind = 4 ) y call date_and_time ( values = values ) y = values(1) m = values(2) d = values(3) h = values(5) n = values(6) s = values(7) mm = values(8) if ( h < 12 ) then ampm = 'AM' else if ( h == 12 ) then if ( n == 0 .and. s == 0 ) then ampm = 'Noon' else ampm = 'PM' end if else h = h - 12 if ( h < 12 ) then ampm = 'PM' else if ( h == 12 ) then if ( n == 0 .and. s == 0 ) then ampm = 'Midnight' else ampm = 'AM' end if end if end if write ( *, '(i2,1x,a,1x,i4,2x,i2,a1,i2.2,a1,i2.2,a1,i3.3,1x,a)' ) & d, trim ( month(m) ), y, h, ':', n, ':', s, '.', mm, trim ( ampm ) return end subroutine van_der_corput ( r ) !*****************************************************************************80 ! !! VAN_DER_CORPUT computes the next element in the van der Corput sequence. ! ! Discussion: ! ! The internal variables SEED and BASE control the van der Corput sequence. ! The value of SEED is incremented by one on each call. ! ! Licensing: ! ! This code is distributed under the GNU LGPL license. ! ! Modified: ! ! 28 August 2002 ! ! Author: ! ! John Burkardt ! ! Reference: ! ! Johannes van der Corput, ! Verteilungsfunktionen I & II, ! Nederl. Akad. Wetensch. Proc., ! Volume 38, 1935, pages 813-820, pages 1058-1066. ! ! Parameters: ! ! Output, real ( kind = 8 ) R, the next element of the van der ! Corput sequence. ! implicit none integer ( kind = 4 ) base integer ( kind = 4 ), parameter :: inc = 1 real ( kind = 8 ) r integer ( kind = 4 ) seed call van_der_corput_memory ( 'GET', 'SEED', seed ) call van_der_corput_memory ( 'GET', 'BASE', base ) call i4_to_van_der_corput ( seed, base, r ) call van_der_corput_memory ( 'INC', 'SEED', inc ) return end subroutine van_der_corput_base_get ( base ) !*****************************************************************************80 ! !! VAN_DER_CORPUT_BASE_GET gets the base for a van der Corput sequence. ! ! Licensing: ! ! This code is distributed under the GNU LGPL license. ! ! Modified: ! ! 28 August 2002 ! ! Author: ! ! John Burkardt ! ! Reference: ! ! Johannes van der Corput, ! Verteilungsfunktionen I & II, ! Nederl. Akad. Wetensch. Proc., ! Volume 38, 1935, pages 813-820, pages 1058-1066. ! ! Parameters: ! ! Output, integer ( kind = 4 ) BASE, the base for the van der Corput ! sequence. ! implicit none integer ( kind = 4 ) base call van_der_corput_memory ( 'GET', 'BASE', base ) return end subroutine van_der_corput_base_set ( base ) !*****************************************************************************80 ! !! VAN_DER_CORPUT_BASE_SET sets the base for a van der Corput sequence. ! ! Licensing: ! ! This code is distributed under the GNU LGPL license. ! ! Modified: ! ! 28 August 2002 ! ! Author: ! ! John Burkardt ! ! Reference: ! ! Johannes van der Corput, ! Verteilungsfunktionen I & II, ! Nederl. Akad. Wetensch. Proc., ! Volume 38, 1935, pages 813-820, pages 1058-1066. ! ! Parameters: ! ! Input, integer ( kind = 4 ) BASE, the van der Corput base, which is ! typically a prime number. BASE must be greater than 1. ! implicit none integer ( kind = 4 ) base call van_der_corput_memory ( 'SET', 'BASE', base ) return end subroutine van_der_corput_memory ( action, name, value ) !*****************************************************************************80 ! !! VAN_DER_CORPUT_MEMORY stores data for the van der Corput sequence. ! ! Licensing: ! ! This code is distributed under the GNU LGPL license. ! ! Modified: ! ! 07 January 2003 ! ! Author: ! ! John Burkardt ! ! Reference: ! ! Johannes van der Corput, ! Verteilungsfunktionen I & II, ! Nederl. Akad. Wetensch. Proc., ! Volume 38, 1935, pages 813-820, pages 1058-1066. ! ! Parameters: ! ! Input, character ( len = * ) ACTION, the desired action. ! 'GET' means get the value of a particular quantity. ! 'SET' means set the value of a particular quantity. ! 'INC' means increment the value of a particular quantity. ! ! Input, character ( len = * ) NAME, the name of the quantity. ! 'BASE' means the van der Corput base. ! 'SEED' means the (current) van der Corput seed. ! ! Input/output, integer ( kind = 4 ) VALUE, contains a value. ! If ACTION is 'SET', then on input, VALUE contains the value to be assigned ! to the internal variable. ! If ACTION is 'GET', then on output, VALUE contains the value of ! the specified internal variable. ! If ACTION is 'INC', then on input, VALUE contains the increment to ! be added to the specified internal variable. ! implicit none character ( len = * ) action integer ( kind = 4 ), save :: base = 2 character ( len = * ) name integer ( kind = 4 ), save :: seed = 1 integer ( kind = 4 ) value ! ! Set ! if ( action(1:1) == 'S' .or. action(1:1) == 's' ) then if ( name(1:1) == 'B' .or. name(1:1) == 'b' ) then if ( value <= 1 ) then write ( *, '(a)' ) ' ' write ( *, '(a)' ) 'VAN_DER_CORPUT_MEMORY - Fatal error!' write ( *, '(a)' ) ' The input base BASE is <= 1!' write ( *, '(a,i6)' ) ' BASE = ', value stop 1 end if base = value else if ( name(1:1) == 'S' .or. name(1:1) == 's' ) then if ( value < 0 ) then write ( *, '(a)' ) ' ' write ( *, '(a)' ) 'VAN_DER_CORPUT_MEMORY - Fatal error!' write ( *, '(a)' ) ' The input base SEED is < 0!' write ( *, '(a,i6)' ) ' SEED = ', value stop 1 end if seed = value else write ( *, '(a)' ) ' ' write ( *, '(a)' ) 'VAN_DER_CORPUT_MEMORY - Fatal error!' write ( *, '(a)' ) ' Unrecognized variable name!' write ( *, '(a,i6)' ) ' NAME = ' // trim ( name ) stop 1 end if ! ! Get ! else if ( action(1:1) == 'G' .or. action(1:1) == 'g' ) then if ( name(1:1) == 'B' .or. name(1:1) == 'b' ) then value = base else if ( name(1:1) == 'S' .or. name(1:1) == 's' ) then value = seed else write ( *, '(a)' ) ' ' write ( *, '(a)' ) 'VAN_DER_CORPUT_MEMORY - Fatal error!' write ( *, '(a)' ) ' Unrecognized variable name!' write ( *, '(a,i6)' ) ' NAME = ' // trim ( name ) stop 1 end if ! ! Increment ! else if ( action(1:1) == 'I' .or. action(1:1) == 'i' ) then if ( name(1:1) == 'B' .or. name(1:1) == 'b' ) then base = base + value else if ( name(1:1) == 'S' .or. name(1:1) == 's' ) then seed = seed + value else write ( *, '(a)' ) ' ' write ( *, '(a)' ) 'VAN_DER_CORPUT_MEMORY - Fatal error!' write ( *, '(a)' ) ' Unrecognized variable name!' write ( *, '(a,i6)' ) ' NAME = ' // trim ( name ) stop 1 end if ! ! Unrecognized action. ! else write ( *, '(a)' ) ' ' write ( *, '(a)' ) 'VAN_DER_CORPUT_MEMORY - Fatal error!' write ( *, '(a)' ) ' Unrecognized action!' write ( *, '(a,i6)' ) ' ACTION = ' // trim ( action ) stop 1 end if return end subroutine van_der_corput_seed_get ( seed ) !*****************************************************************************80 ! !! VAN_DER_CORPUT_SEED_GET gets the "seed" for the van der Corput sequence. ! ! Licensing: ! ! This code is distributed under the GNU LGPL license. ! ! Modified: ! ! 26 February 2001 ! ! Author: ! ! John Burkardt ! ! Reference: ! ! Johannes van der Corput, ! Verteilungsfunktionen I & II, ! Nederl. Akad. Wetensch. Proc., ! Volume 38, 1935, pages 813-820, pages 1058-1066. ! ! Parameters: ! ! Output, integer ( kind = 4 ) SEED, the current seed for the ! van der Corput sequence. ! implicit none integer ( kind = 4 ) seed call van_der_corput_memory ( 'GET', 'SEED', seed ) return end subroutine van_der_corput_seed_set ( seed ) !*****************************************************************************80 ! !! VAN_DER_CORPUT_SEED_SET sets the "seed" for the van der Corput sequence. ! ! Discussion: ! ! Calling VAN_DER_CORPUT repeatedly returns the elements of the ! van der Corput sequence in order, starting with element number 1. ! An internal counter, called SEED, keeps track of the next element ! to return. Each time the routine is called, the SEED-th element ! is computed, and then SEED is incremented by 1. ! ! To restart the van der Corput sequence, it is only necessary to reset ! SEED to 1. It might also be desirable to reset SEED to some other value. ! This routine allows the user to specify any value of SEED. ! ! The default value of SEED is 1, which restarts the van der Corput sequence. ! ! Licensing: ! ! This code is distributed under the GNU LGPL license. ! ! Modified: ! ! 26 February 2001 ! ! Author: ! ! John Burkardt ! ! Reference: ! ! Johannes van der Corput, ! Verteilungsfunktionen I & II, ! Nederl. Akad. Wetensch. Proc., ! Volume 38, 1935, pages 813-820, pages 1058-1066. ! ! Parameters: ! ! Input, integer ( kind = 4 ) SEED, the seed for the van der Corput ! sequence. SEED should be nonnegative. SEED = 0 is allowed. ! implicit none integer ( kind = 4 ) seed call van_der_corput_memory ( 'SET', 'SEED', seed ) return end subroutine van_der_corput_sequence ( n, r ) !*****************************************************************************80 ! !! VAN_DER_CORPUT_SEQUENCE: next N elements in the van der Corput sequence. ! ! Licensing: ! ! This code is distributed under the GNU LGPL license. ! ! Modified: ! ! 28 August 2002 ! ! Author: ! ! John Burkardt ! ! Reference: ! ! Johannes van der Corput, ! Verteilungsfunktionen I & II, ! Nederl. Akad. Wetensch. Proc., ! Volume 38, 1935, pages 813-820, pages 1058-1066. ! ! Parameters: ! ! Input, integer ( kind = 4 ) N, the number of elements desired. ! ! Output, real ( kind = 8 ) R(N), the next N elements of the van der ! Corput sequence. ! implicit none integer ( kind = 4 ) n integer ( kind = 4 ) base real ( kind = 8 ) r(n) integer ( kind = 4 ) seed call van_der_corput_memory ( 'GET', 'SEED', seed ) call van_der_corput_memory ( 'GET', 'BASE', base ) call i4_to_van_der_corput_sequence ( seed, base, n, r ) call van_der_corput_memory ( 'INC', 'SEED', n ) return end subroutine vdc_numerator_sequence ( n, p ) !*****************************************************************************80 ! !! VDC_NUMERATOR_SEQUENCE: van der Corput numerator sequence base 2. ! ! Discussion: ! ! The classical van der Corput sequence, base 2, can be considered ! as a way of enumerating the dyadic fractions P/2^K in an order of ! increasing denominator. ! ! If we fix a value of K, then the first (2^K) - 1 items in the ! sequence are fractions strictly between 0 and 1, which can be written ! as P/2^K where 0 < P < 2^K. ! ! This function determines the numerator sequence, that is, the values ! P, which is interesting in its own right. Note that the P sequence ! is "nested" in the sense that if 2^(K-1) <= N1 < N2 < 2^(K), then the ! sequence for N2 will begin with the sequence for N1. ! ! The I-th value in the sequence can be determined by writing ! the integer I in binary using K digits, and reversing the order. ! ! N = 10 ! ! 2^3 = 8 <= 10 < 16 = 2^4 ! ! 1 0001 1000 8 ! 2 0010 0100 4 ! 3 0011 1100 12 ! 4 0100 0010 2 ! 5 0101 1010 10 ! 6 0110 0110 6 ! 7 0111 1110 14 ! 8 1000 0001 1 ! 9 1001 1001 9 ! 10 1010 0101 5 ! ! Licensing: ! ! This code is distributed under the GNU LGPL license. ! ! Modified: ! ! 03 February 2011 ! ! Author: ! ! John Burkardt ! ! Reference: ! ! John Halton, ! On the efficiency of certain quasi-random sequences of points ! in evaluating multi-dimensional integrals, ! Numerische Mathematik, ! Volume 2, pages 84-90, 1960. ! ! Johannes van der Corput, ! Verteilungsfunktionen I & II, ! Nederl. Akad. Wetensch. Proc., ! Volume 38, 1935, pages 813-820, pages 1058-1066. ! ! Parameters: ! ! Input, integer ( kind = 4 ) N, the number of elements to compute. ! ! Output, integer ( kind = 4 ) P(N), the elements of the van der Corput ! numerator sequence base 2. ! implicit none integer ( kind = 4 ) n integer ( kind = 4 ) d integer ( kind = 4 ) i integer ( kind = 4 ) i4_log_2 integer ( kind = 4 ) j integer ( kind = 4 ) n_log_2 integer ( kind = 4 ) p(n) integer ( kind = 4 ) s ! ! Carry out the computation. ! p(1:n) = 0 n_log_2 = i4_log_2 ( n ) + 1 do i = 1, n s = i do j = 1, n_log_2 d = mod ( s, 2 ) p(i) = 2 * p(i) + d s = s / 2 end do end do return end