arb/arb_hypgeom/test/t-legendre_p_ui_deriv_bound.c

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/*
Copyright (C) 2017 Fredrik Johansson
This file is part of Arb.
Arb is free software: you can redistribute it and/or modify it under
the terms of the GNU Lesser General Public License (LGPL) as published
by the Free Software Foundation; either version 2.1 of the License, or
(at your option) any later version. See <http://www.gnu.org/licenses/>.
*/
#include "arb_hypgeom.h"
int main()
{
slong iter;
flint_rand_t state;
flint_printf("legendre_p_ui_deriv_bound....");
fflush(stdout);
flint_randinit(state);
for (iter = 0; iter < 10000 * arb_test_multiplier(); iter++)
{
arb_t x, x2sub1, y, z;
mag_t m1, m2, exact;
ulong n;
slong prec;
arb_init(x);
arb_init(x2sub1);
arb_init(y);
arb_init(z);
mag_init(m1);
mag_init(m2);
mag_init(exact);
n = n_randtest(state) % 10000;
prec = 64;
arb_randtest(x, state, 2 * prec, 0);
mag_zero(arb_radref(x));
while (arf_cmpabs_2exp_si(arb_midref(x), 0) >= 0)
arb_mul_2exp_si(x, x, -1);
arb_mul_2exp_si(x, x, -n_randint(state, 10));
arb_mul(x2sub1, x, x, 2 * prec);
arb_sub_ui(x2sub1, x2sub1, 1, 2 * prec);
arb_neg(x2sub1, x2sub1);
arb_hypgeom_legendre_p_ui_deriv_bound(m1, m2, n, x, x2sub1);
arb_hypgeom_legendre_p_ui(y, z, n, x, prec);
arb_get_mag_lower(exact, z);
if (mag_cmp(m1, exact) < 0)
{
flint_printf("FAIL: first derivative\n\n");
flint_printf("n = %wu\n\n", n);
flint_printf("x = "); arb_printn(x, 50, 0); flint_printf("\n\n");
flint_printf("z = "); arb_printn(z, 50, 0); flint_printf("\n\n");
flint_printf("m1 = "); mag_printd(m1, 15); flint_printf("\n\n");
flint_abort();
}
arb_mul(z, z, x, prec);
arb_mul_2exp_si(z, z, 1);
arb_mul_ui(y, y, n, prec);
arb_mul_ui(y, y, n + 1, prec);
arb_sub(z, z, y, prec);
arb_div(z, z, x2sub1, prec);
arb_get_mag_lower(exact, z);
if (mag_cmp(m2, exact) < 0)
{
flint_printf("FAIL: second derivative\n\n");
flint_printf("n = %wu\n\n", n);
flint_printf("x = "); arb_printn(x, 50, 0); flint_printf("\n\n");
flint_printf("z = "); arb_printn(z, 50, 0); flint_printf("\n\n");
flint_printf("m2 = "); mag_printd(m2, 15); flint_printf("\n\n");
flint_abort();
}
arb_clear(x);
arb_clear(x2sub1);
arb_clear(y);
arb_clear(z);
mag_clear(m1);
mag_clear(m2);
mag_clear(exact);
}
flint_randclear(state);
flint_cleanup();
flint_printf("PASS\n");
return EXIT_SUCCESS;
}