libm: fix tgamma to actually do return true gamma function

Signed-off-by: Denys Vlasenko <vda.linux@googlemail.com>

1 files changed, 73 insertions, 0 deletions

diff --git a/test/math/gamma.c b/test/math/gamma.c
new file mode 100644
index 000000000..69c10afa4
--- /dev/null
+++ b/test/math/gamma.c
@@ -0,0 +1,73 @@
+#include <math.h>
+#include <float.h>
+#include <stdlib.h>
+#include <stdint.h>
+#include <stdio.h>
+
+#define check_d1(func, param, expected) \
+do { \
+	int err; hex_union ur; hex_union up; \
+	double result = func(param); up.f = param; ur.f = result; \
+	errors += (err = (result != (expected))); \
+	err \
+	? printf("FAIL: %s(%g/"HEXFMT")=%g/"HEXFMT" (expected %g)\n", \
+		#func, (double)(param), (long long)up.hex, result, (long long)ur.hex, (double)(expected)) \
+	: printf("PASS: %s(%g)=%g\n", #func, (double)(param), result); \
+} while (0)
+
+#define HEXFMT "%08llx"
+typedef union {
+	double f;
+	uint64_t hex;
+} hex_union;
+double result;
+
+#define M_2_SQRT_PIl   3.5449077018110320545963349666822903L   /* 2 sqrt (M_PIl)  */
+#define M_SQRT_PIl     1.7724538509055160272981674833411451L   /* sqrt (M_PIl)  */
+
+double zero = 0.0;
+double minus_zero = 0.0;
+double nan_value = 0.0;
+int errors = 0;
+
+int main(void)
+{
+        nan_value /= nan_value;
+        minus_zero = copysign(zero, -1.0);
+
+	//check_d1(tgamma, HUGE_VAL, NAN);
+	//check_d1(tgamma, negative_integer, NAN);
+	check_d1(tgamma, 0.0, HUGE_VAL); /* pole */
+	check_d1(tgamma, minus_zero, -HUGE_VAL); /* pole */
+	check_d1(tgamma, DBL_MAX/2, HUGE_VAL); /* overflow to inf */
+	check_d1(tgamma, DBL_MAX, HUGE_VAL); /* overflow to inf */
+	check_d1(tgamma, HUGE_VAL, HUGE_VAL); /* overflow to inf */
+	check_d1(tgamma, 7, 2*3*4*5*6); /* normal value */
+	check_d1(tgamma, -0.5, -M_2_SQRT_PIl); /* normal value (testing negative points) */
+
+	check_d1(lgamma, -HUGE_VAL, HUGE_VAL);
+	//check_d1(lgamma, HUGE_VAL, NAN);
+	check_d1(lgamma, 0.0, HUGE_VAL); /* pole */
+	check_d1(lgamma, minus_zero, HUGE_VAL); /* pole */
+	check_d1(lgamma, 1.0, 0.0);
+	check_d1(lgamma, 2.0, 0.0);
+	check_d1(lgamma, DBL_MAX/2, HUGE_VAL); /* overflow to inf */
+	check_d1(lgamma, DBL_MAX, HUGE_VAL); /* overflow to inf */
+	check_d1(lgamma, HUGE_VAL, HUGE_VAL); /* overflow to inf */
+	check_d1(lgamma, 7, log(2*3*4*5*6)); /* normal value */
+
+	/* In glibc, gamma == lgamma. (In BSD, it's == tgamma */
+	check_d1(gamma, -HUGE_VAL, HUGE_VAL);
+	//check_d1(gamma, HUGE_VAL, NAN);
+	check_d1(gamma, 0.0, HUGE_VAL); /* pole */
+	check_d1(gamma, minus_zero, HUGE_VAL); /* pole */
+	check_d1(gamma, 1.0, 0.0);
+	check_d1(gamma, 2.0, 0.0);
+	check_d1(gamma, DBL_MAX/2, HUGE_VAL); /* overflow to inf */
+	check_d1(gamma, DBL_MAX, HUGE_VAL); /* overflow to inf */
+	check_d1(gamma, HUGE_VAL, HUGE_VAL); /* overflow to inf */
+	check_d1(gamma, 7, log(2*3*4*5*6)); /* normal value */
+
+	printf("Errors: %d\n", errors);
+	return errors;
+}