/* nag_1d_quad_inf_1 (d01smc) Example Program. * * Copyright 1998 Numerical Algorithms Group. * * Mark 5, 1998. * Mark 6 revised, 2000. * Mark 7 revised, 2001. * */ #include #include #include #include #include #ifdef __cplusplus extern "C" { #endif static double NAG_CALL f(double x, Nag_User *comm); #ifdef __cplusplus } #endif int main(void) { static Integer use_comm[1] = {1}; Integer exit_status = 0; double a; double epsabs, abserr, epsrel, result; Nag_QuadProgress qp; Integer max_num_subint; NagError fail; Nag_User comm; INIT_FAIL(fail); printf("nag_1d_quad_inf_1 (d01smc) Example Program Results\n"); /* For communication with user-supplied functions: */ comm.p = (Pointer)&use_comm; epsabs = 0.0; epsrel = 0.0001; a = 0.0; max_num_subint = 200; /* nag_1d_quad_inf_1 (d01smc). * One-dimensional adaptive quadrature over infinite or * semi-infinite interval, thread-safe */ nag_1d_quad_inf_1(f, Nag_UpperSemiInfinite, a, epsabs, epsrel, max_num_subint, &result, &abserr, &qp, &comm, &fail); printf("a - lower limit of integration = %10.4f\n", a); printf("b - upper limit of integration = infinity\n"); printf("epsabs - absolute accuracy requested = %11.2e\n", epsabs); printf("epsrel - relative accuracy requested = %11.2e\n\n", epsrel); if (fail.code != NE_NOERROR) printf("Error from nag_1d_quad_inf_1 (d01smc) %s\n", fail.message); if (fail.code != NE_INT_ARG_LT && fail.code != NE_BAD_PARAM && fail.code != NE_ALLOC_FAIL && fail.code != NE_NO_LICENCE) { printf("result - approximation to the integral = %9.5f\n", result); printf("abserr - estimate of the absolute error = %11.2e\n", abserr); printf("qp.fun_count - number of function evaluations = %4ld\n", qp.fun_count); printf("qp.num_subint - number of subintervals used = %4ld\n", qp.num_subint); /* Free memory used by qp */ NAG_FREE(qp.sub_int_beg_pts); NAG_FREE(qp.sub_int_end_pts); NAG_FREE(qp.sub_int_result); NAG_FREE(qp.sub_int_error); } else { exit_status = 1; goto END; } END: return exit_status; } static double NAG_CALL f(double x, Nag_User *comm) { Integer *use_comm = (Integer *)comm->p; if (use_comm[0]) { printf("(User-supplied callback f, first invocation.)\n"); use_comm[0] = 0; } return 1.0/((x+1.0)*sqrt(x)); }