PATTERSON_RULE_COMPUTE is a FORTRAN90 program which computes the points and weights of a 1D Gauss-Patterson quadrature rule of order 1, 3, 7, 15, 31, 63, 127, 255 or 511, to approximate integrals in the interval [A,B], as specified by the user.
The rule is written to three files for easy use as input to other programs.
The program is based on Patterson's ACM TOMS algorithm 672, which is actually designed for the more general problem of creating a more accurate quadrature rule from any given one by adding intermediate points.
This program differs from the patterson_rule program in that it actually computes the points and weights directly, rather than simply looking them up in a table.
The Gauss-Patterson quadrature is a nested family which begins with the Gauss-Legendre rules of orders 1 and 3, and then succesively inserts one new abscissa in each subinterval. Thus, after the second rule, the Gauss-Patterson rules do not have the super-high precision of the Gauss-Legendre rules. They trade this precision in exchange for the advantages of nestedness. This means that Gauss-Patterson rules are only available for orders of 1, 3, 7, 15, 31, 63, 127, 255 or 511.
The standard Gauss-Patterson quadrature rule is used as follows:
Integral ( A <= x <= B ) f(x) dxis to be approximated by
Sum ( 1 <= i <= order ) w(i) * f(x(i))
The polynomial precision of a Gauss-Patterson rule can be checked numerically by the INT_EXACTNESS_LEGENDRE program. We should expect
Index | Order | Free+Fixed | Expected Precision | Actual Precision |
---|---|---|---|---|
0 | 1 | 1 + 0 | 2*1+0-1=1 | 1 |
1 | 3 | 3 + 0 | 2*3+0-1=5 | 5 |
2 | 7 | 4 + 3 | 2*4+3-1=10 | 10 + 1 = 11 |
3 | 15 | 8 + 7 | 2*8+7-1=22 | 22 + 1 = 23 |
4 | 31 | 16 + 15 | 2*16+15-1=46 | 46 + 1 = 47 |
5 | 63 | 32 + 31 | 2*32+31-1=94 | 94 + 1 = 95 |
6 | 127 | 64 + 63 | 2*64+63-1=190 | 190 + 1 = 191 |
7 | 255 | 128 + 127 | 2*128+127-1=382 | 382 + 1 = 383 |
8 | 511 | 256 + 255 | 2*256+255-1=766 | 766 + 1 = 767 |
patterson_rule_compute order a b filenamewhere
PATTERSON_RULE_COMPUTE is available in a FORTRAN90 version.
The computer code and data files described and made available on this web page are distributed under the GNU LGPL license.
CCN_RULE, a FORTRAN90 program which defines a nested Clenshaw Curtis quadrature rule.
CHEBYSHEV1_RULE, a FORTRAN90 program which can compute and print a Gauss-Chebyshev type 1 quadrature rule.
CHEBYSHEV2_RULE, a FORTRAN90 program which can compute and print a Gauss-Chebyshev type 2 quadrature rule.
CLENSHAW_CURTIS_RULE, a FORTRAN90 program which defines a Clenshaw Curtis quadrature rule.
GEGENBAUER_RULE, a FORTRAN90 program which can compute and print a Gauss-Gegenbauer quadrature rule.
GEN_HERMITE_RULE, a FORTRAN90 program which can compute and print a generalized Gauss-Hermite quadrature rule.
GEN_LAGUERRE_RULE, a FORTRAN90 program which can compute and print a generalized Gauss-Laguerre quadrature rule.
HERMITE_RULE, a FORTRAN90 program which can compute and print a Gauss-Hermite quadrature rule.
INT_EXACTNESS_LEGENDRE, a FORTRAN90 program which checks the polynomial exactness of a Gauss-Legendre quadrature rule.
JACOBI_RULE, a FORTRAN90 program which can compute and print a Gauss-Jacobi quadrature rule.
KRONROD, a FORTRAN90 library which can compute a Gauss and Gauss-Kronrod pair of quadrature rules of arbitrary order, by Robert Piessens, Maria Branders.
LAGUERRE_RULE, a FORTRAN90 program which can compute and print a Gauss-Laguerre quadrature rule.
LEGENDRE_RULE, a FORTRAN90 program which can compute and print a Gauss-Legendre quadrature rule.
LEGENDRE_RULE_FAST, a FORTRAN90 program which uses a fast (order N) algorithm to compute a Gauss-Legendre quadrature rule of given order.
LOGNORMAL_RULE, a FORTRAN90 program which can compute and print a quadrature rule for functions of a variable whose logarithm is normally distributed.
PATTERSON_RULE, a FORTRAN90 program which returns the points and weights of a 1D Gauss-Patterson quadrature rule of order 1, 3, 7, 15, 31, 63, 127, 255 or 511.
TOMS699,
a FORTRAN77 library which
implements a new representation of Patterson's quadrature formula;
this is ACM TOMS algorithm 699.
TRUNCATED_NORMAL_RULE, a FORTRAN90 program which computes a quadrature rule for a normal distribution that has been truncated to [A,+oo), (-oo,B] or [A,B].
The command
patterson_rule_compute 15 -1.0 +1.0 gp015creates the following "region", "weight" and "point" files:
You can go up one level to the FORTRAN90 source codes.