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Further refine hypot implementation

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Thanks go to Fabian Giesen on Twitter for code review and advice.
This commit is contained in:
Justine Tunney 2021-02-21 12:53:01 -08:00
parent 4a5698b5c9
commit c6c9b5dfde
4 changed files with 66 additions and 18 deletions
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9
libc/tinymath/hypot.c
View file

@ -22,10 +22,13 @@
* Returns euclidean distance.
*/
double hypot(double a, double b) {
double r;
double r, t;
if (isinf(a) || isinf(b)) return INFINITY;
if (isunordered(a, b)) return NAN;
if (!a) return 0;
a = fabs(a);
b = fabs(b);
if (a < b) t = b, b = a, a = t;
if (!a) return b;
r = b / a;
return fabs(a) * sqrt(1 + r * r);
return a * sqrt(1 + r * r);
}

9
libc/tinymath/hypotf.c
View file

@ -22,10 +22,13 @@
* Returns euclidean distance.
*/
float hypotf(float a, float b) {
float r;
float r, t;
if (isinf(a) || isinf(b)) return INFINITY;
if (isunordered(a, b)) return NAN;
if (!a) return 0;
a = fabsf(a);
b = fabsf(b);
if (a < b) t = b, b = a, a = t;
if (!a) return b;
r = b / a;
return fabsf(a) * sqrtf(1 + r * r);
return a * sqrtf(1 + r * r);
}

9
libc/tinymath/hypotl.c
View file

@ -22,10 +22,13 @@
* Returns euclidean distance.
*/
long double hypotl(long double a, long double b) {
long double r;
long double r, t;
if (isinf(a) || isinf(b)) return INFINITY;
if (isunordered(a, b)) return NAN;
if (!a) return 0;
a = fabsl(a);
b = fabsl(b);
if (a < b) t = b, b = a, a = t;
if (!a) return b;
r = b / a;
return fabsl(a) * sqrtl(1 + r * r);
return a * sqrtl(1 + r * r);
}

57
test/libc/tinymath/hypot_test.c
View file

@ -23,8 +23,21 @@
TEST(hypot, test) {
EXPECT_STREQ("0", gc(xdtoa(hypot(0, 0))));
EXPECT_STREQ("3", gc(xdtoa(hypot(3, 0))));
EXPECT_STREQ("3", gc(xdtoa(hypot(0, 3))));
EXPECT_STREQ("5", gc(xdtoa(hypot(3, 4))));
EXPECT_STREQ("5", gc(xdtoa(hypot(4, 3))));
EXPECT_STREQ("5", gc(xdtoa(hypot(3, -4))));
EXPECT_STREQ("5", gc(xdtoa(hypot(-4, 3))));
EXPECT_STREQ("5", gc(xdtoa(hypot(-3, 4))));
EXPECT_STREQ("5", gc(xdtoa(hypot(4, -3))));
EXPECT_STREQ("5", gc(xdtoa(hypot(-3, -4))));
EXPECT_STREQ("5", gc(xdtoa(hypot(-4, -3))));
EXPECT_STREQ("1.414213562373095", gc(xdtoa(hypot(1, 1))));
EXPECT_STREQ("1.414213562373095", gc(xdtoa(hypot(1, -1))));
EXPECT_STREQ("1.414213562373095", gc(xdtoa(hypot(-1, 1))));
EXPECT_STREQ("1.414213626012708", gc(xdtoa(hypot(1.0000001, .99999999))));
EXPECT_STREQ("1.414213626012708", gc(xdtoa(hypot(.99999999, 1.0000001))));
EXPECT_STREQ("1.414213562373095e+154", gc(xdtoa(hypot(1e154, 1e154))));
EXPECT_STREQ("NAN", gc(xdtoa(hypot(0, NAN))));
EXPECT_STREQ("NAN", gc(xdtoa(hypot(NAN, 0))));
@ -38,23 +51,49 @@ TEST(hypot, test) {
TEST(hypotf, test) {
EXPECT_STREQ("0", gc(xdtoa(hypotf(0, 0))));
EXPECT_STREQ("3", gc(xdtoa(hypotf(3, 0))));
EXPECT_STREQ("3", gc(xdtoa(hypotf(0, 3))));
EXPECT_STREQ("5", gc(xdtoa(hypotf(3, 4))));
EXPECT_STREQ("5", gc(xdtoa(hypotf(4, 3))));
EXPECT_STREQ("5", gc(xdtoa(hypotf(3, -4))));
EXPECT_STREQ("5", gc(xdtoa(hypotf(-4, 3))));
EXPECT_STREQ("5", gc(xdtoa(hypotf(-3, 4))));
EXPECT_STREQ("5", gc(xdtoa(hypotf(4, -3))));
EXPECT_STREQ("5", gc(xdtoa(hypotf(-3, -4))));
EXPECT_STREQ("5", gc(xdtoa(hypotf(-4, -3))));
EXPECT_STREQ("1.414214", gc(xdtoaf(hypotf(1, 1))));
EXPECT_STREQ("1.414214", gc(xdtoaf(hypotf(1, -1))));
EXPECT_STREQ("1.414214", gc(xdtoaf(hypotf(-1, 1))));
EXPECT_STREQ("1.414214", gc(xdtoaf(hypotf(1.000001, 0.999999))));
EXPECT_STREQ("1.414214", gc(xdtoaf(hypotf(0.999999, 1.000001))));
EXPECT_STREQ("1.414214e+38", gc(xdtoaf(hypotf(1e38, 1e38))));
EXPECT_STREQ("NAN", gc(xdtoa(hypotf(0, NAN))));
EXPECT_STREQ("NAN", gc(xdtoa(hypotf(NAN, 0))));
EXPECT_STREQ("NAN", gc(xdtoa(hypotf(NAN, NAN))));
EXPECT_STREQ("INFINITY", gc(xdtoa(hypotf(INFINITY, 0))));
EXPECT_STREQ("INFINITY", gc(xdtoa(hypotf(0, INFINITY))));
EXPECT_STREQ("INFINITY", gc(xdtoa(hypotf(INFINITY, NAN))));
EXPECT_STREQ("INFINITY", gc(xdtoa(hypotf(NAN, INFINITY))));
EXPECT_STREQ("INFINITY", gc(xdtoa(hypotf(INFINITY, INFINITY))));
EXPECT_STREQ("NAN", gc(xdtoaf(hypotf(0, NAN))));
EXPECT_STREQ("NAN", gc(xdtoaf(hypotf(NAN, 0))));
EXPECT_STREQ("NAN", gc(xdtoaf(hypotf(NAN, NAN))));
EXPECT_STREQ("INFINITY", gc(xdtoaf(hypotf(INFINITY, 0))));
EXPECT_STREQ("INFINITY", gc(xdtoaf(hypotf(0, INFINITY))));
EXPECT_STREQ("INFINITY", gc(xdtoaf(hypotf(INFINITY, NAN))));
EXPECT_STREQ("INFINITY", gc(xdtoaf(hypotf(NAN, INFINITY))));
EXPECT_STREQ("INFINITY", gc(xdtoaf(hypotf(INFINITY, INFINITY))));
}
TEST(hypotl, test) {
TEST(hypotll, test) {
EXPECT_STREQ("0", gc(xdtoa(hypotl(0, 0))));
EXPECT_STREQ("3", gc(xdtoa(hypotl(3, 0))));
EXPECT_STREQ("3", gc(xdtoa(hypotl(0, 3))));
EXPECT_STREQ("5", gc(xdtoa(hypotl(3, 4))));
EXPECT_STREQ("5", gc(xdtoa(hypotl(4, 3))));
EXPECT_STREQ("5", gc(xdtoa(hypotl(3, -4))));
EXPECT_STREQ("5", gc(xdtoa(hypotl(-4, 3))));
EXPECT_STREQ("5", gc(xdtoa(hypotl(-3, 4))));
EXPECT_STREQ("5", gc(xdtoa(hypotl(4, -3))));
EXPECT_STREQ("5", gc(xdtoa(hypotl(-3, -4))));
EXPECT_STREQ("5", gc(xdtoa(hypotl(-4, -3))));
EXPECT_STREQ("1.414213562373095", gc(xdtoa(hypotl(1, 1))));
EXPECT_STREQ("1.414213562373095", gc(xdtoa(hypotl(1, -1))));
EXPECT_STREQ("1.414213562373095", gc(xdtoa(hypotl(-1, 1))));
EXPECT_STREQ("1.414213626012708", gc(xdtoa(hypotl(1.0000001, .99999999))));
EXPECT_STREQ("1.414213626012708", gc(xdtoa(hypotl(.99999999, 1.0000001))));
EXPECT_STREQ("1.414213562373095e+4931", gc(xdtoa(hypotl(1e4931L, 1e4931L))));
EXPECT_STREQ("NAN", gc(xdtoa(hypotl(0, NAN))));
EXPECT_STREQ("NAN", gc(xdtoa(hypotl(NAN, 0))));