/* nag_bessel_i_alpha (s18ejc) Example Program. * * Copyright 2000 Numerical Algorithms Group. * * NAG C Library * * Mark 6, 2000. * Mark 8 revised, 2004. */ #include #include #include #include int main(void) { Complex *b = 0; Integer exit_status = 0, i, nl; NagError fail; double a, alpha, d, x; INIT_FAIL(fail); /* Skip heading in data file */ scanf("%*[^\n]"); printf("nag_bessel_i_alpha (s18ejc) Example Program Results\n"); if (!(b = NAG_ALLOC(101, Complex))) { printf("Allocation failure\n"); exit_status = -1; goto END; } while (scanf("%lf %lf %ld%*[^\n]", &x, &a, &nl) != EOF) { printf(" x a nl\n"); printf("%4.1f %4.1f %6ld\n\n", x, a, nl); /* nag_bessel_i_alpha (s18ejc). * Modified Bessel functions I_(alpha+n-1)(x) or * I_(alpha-n+1)(x) for real x != 0, non-negative * alpha < 1 and n = 1,2,...,|N|+1 */ nag_bessel_i_alpha(x, a, nl, b, &fail); if (fail.code == NE_NOERROR) { printf(" Requested values of I_alpha(X)\n\n"); alpha = a; printf(" alpha I_alpha(X)\n"); for (i = 1; i <= ABS(nl) + 1; ++i) { printf("%13.4e (%13.4e, %13.4e)\n", alpha, b[i - 1].re, b[i - 1].im); d = (double) nl; alpha += SIGN(1.0, d); } } else { printf("Error from nag_bessel_i_alpha (s18ejc).\n%s\n", fail.message); exit_status = 1; goto END; } } END: NAG_FREE(b); return exit_status; } /* main */