Chromium Code Reviews
chromiumcodereview-hr@appspot.gserviceaccount.com (chromiumcodereview-hr) | Please choose your nickname with Settings | Help | Chromium Project | Gerrit Changes | Sign out
(426)

Unified Diff: fusl/src/math/atanhf.c

Issue 1573973002: Add a "fork" of musl as //fusl. (Closed) Base URL: https://github.com/domokit/mojo.git@master
Patch Set: Created 4 years, 11 months ago
Use n/p to move between diff chunks; N/P to move between comments. Draft comments are only viewable by you.
Jump to:
View side-by-side diff with in-line comments
Download patch
« no previous file with comments | « fusl/src/math/atanh.c ('k') | fusl/src/math/atanhl.c » ('j') | no next file with comments »
Expand Comments ('e') | Collapse Comments ('c') | Show Comments Hide Comments ('s')
Index: fusl/src/math/atanhf.c
diff --git a/fusl/src/math/atanhf.c b/fusl/src/math/atanhf.c
new file mode 100644
index 0000000000000000000000000000000000000000..65f07c0f4f26e302f98ee4cc75b471c4204ee829
--- /dev/null
+++ b/fusl/src/math/atanhf.c
@@ -0,0 +1,28 @@
+#include "libm.h"
+
+/* atanh(x) = log((1+x)/(1-x))/2 = log1p(2x/(1-x))/2 ~= x + x^3/3 + o(x^5) */
+float atanhf(float x)
+{
+ union {float f; uint32_t i;} u = {.f = x};
+ unsigned s = u.i >> 31;
+ float_t y;
+
+ /* |x| */
+ u.i &= 0x7fffffff;
+ y = u.f;
+
+ if (u.i < 0x3f800000 - (1<<23)) {
+ if (u.i < 0x3f800000 - (32<<23)) {
+ /* handle underflow */
+ if (u.i < (1<<23))
+ FORCE_EVAL((float)(y*y));
+ } else {
+ /* |x| < 0.5, up to 1.7ulp error */
+ y = 0.5f*log1pf(2*y + 2*y*y/(1-y));
+ }
+ } else {
+ /* avoid overflow */
+ y = 0.5f*log1pf(2*(y/(1-y)));
+ }
+ return s ? -y : y;
+}
« no previous file with comments | « fusl/src/math/atanh.c ('k') | fusl/src/math/atanhl.c » ('j') | no next file with comments »

Powered by Google App Engine
This is Rietveld 408576698