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/* mathews/trapezod.f -- translated by f2c (version 20050501).
You must link the resulting object file with libf2c:
on Microsoft Windows system, link with libf2c.lib;
on Linux or Unix systems, link with .../path/to/libf2c.a -lm
or, if you install libf2c.a in a standard place, with -lf2c -lm
-- in that order, at the end of the command line, as in
cc *.o -lf2c -lm
Source for libf2c is in /netlib/f2c/libf2c.zip, e.g.,
http://www.netlib.org/f2c/libf2c.zip
*/
#ifdef __cplusplus
extern "C" {
#endif
#include "v3p_netlib.h"
/* NUMERICAL METHODS: FORTRAN Programs, (c) John H. Mathews 1994 */
/* To accompany the text: */
/* NUMERICAL METHODS for Mathematics, Science and Engineering, 2nd Ed, 1992 */
/* Prentice Hall, Englewood Cliffs, New Jersey, 07632, U.S.A. */
/* This free software is complements of the author. */
/* Algorithm 7.1 (Composite Trapezoidal Rule). */
/* Section 7.2, Composite Trapezoidal and Simpson's Rule, Page 365 */
/*< SUBROUTINE TRAPRU(F,A,B,M,Trule) >*/
/* Subroutine */ int trapru_(
v3p_netlib_doublereal (*f)(v3p_netlib_doublereal*),
doublereal *a, doublereal *b, integer *m, doublereal *trule
)
{
/* System generated locals */
integer i__1;
/* Local variables */
doublereal h__;
integer k;
doublereal x, sum;
/*< INTEGER K,M >*/
/*< DOUBLE PRECISION A,B,H,Sum,Trule,X >*/
/*< EXTERNAL F >*/
/*< H=(B-A)/M >*/
h__ = (*b - *a) / *m;
/*< Sum=0 >*/
sum = 0.;
/*< DO K=1,M-1 >*/
i__1 = *m - 1;
for (k = 1; k <= i__1; ++k) {
/*< X=A+H*K >*/
x = *a + h__ * k;
/*< Sum=Sum+F(X) >*/
sum += (*f)(&x);
/*< ENDDO >*/
}
/*< Sum=H*(F(A)+F(B)+2*Sum)/2 >*/
sum = h__ * ((*f)(a) + (*f)(b) + sum * 2) / 2;
/*< Trule=Sum >*/
*trule = sum;
/*< RETURN >*/
return 0;
/*< END >*/
} /* trapru_ */
/*< SUBROUTINE XTRAPRU(F,A,B,M,Trule) >*/
/* Subroutine */ int xtrapru_(
v3p_netlib_doublereal (*f)(v3p_netlib_doublereal*),
doublereal *a, doublereal *b, integer * m, doublereal *trule
)
{
/* System generated locals */
integer i__1;
/* Local variables */
doublereal h__;
integer k;
doublereal x, sum;
/* This subroutine uses labeled DO loop(s). */
/*< INTEGER K,M >*/
/*< DOUBLE PRECISION A,B,H,Sum,Trule,X >*/
/*< EXTERNAL F >*/
/*< H=(B-A)/M >*/
h__ = (*b - *a) / *m;
/*< Sum=0 >*/
sum = 0.;
/*< DO 10 K=1,M-1 >*/
i__1 = *m - 1;
for (k = 1; k <= i__1; ++k) {
/*< X=A+H*K >*/
x = *a + h__ * k;
/*< Sum=Sum+F(X) >*/
sum += (*f)(&x);
/*< 10 CONTINUE >*/
/* L10: */
}
/*< Sum=H*(F(A)+F(B)+2*Sum)/2 >*/
sum = h__ * ((*f)(a) + (*f)(b) + sum * 2) / 2;
/*< Trule=Sum >*/
*trule = sum;
/*< RETURN >*/
return 0;
/*< END >*/
} /* xtrapru_ */
#ifdef __cplusplus
}
#endif
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