1 files changed, 48 insertions, 0 deletions
diff --git a/winsup/mingw/mingwex/complex/casinf.c b/winsup/mingw/mingwex/complex/casinf.c
new file mode 100755
index 000000000..a70058b0c
--- /dev/null
+++ b/winsup/mingw/mingwex/complex/casinf.c
@@ -0,0 +1,48 @@
+/*
+   casinf.c
+   Contributed by Danny Smith
+   2004-12-24
+*/
+
+#include <math.h>
+#include <complex.h>
+
+/* casin (Z ) = -I * clog(I * Z + csqrt (1.0 - Z * Z))) */
+
+float complex casinf (float complex Z)
+{
+  float complex Res;
+  float x, y;
+
+  x = __real__ Z;
+  y = __imag__ Z;
+
+  if (y == 0.0f)
+    {
+      __real__ Res = asinf (x);
+      __imag__ Res = 0.0f;
+    }
+  else  /* -I * clog(I * Z + csqrt(1.0 - Z * Z))) */
+    {
+      float complex ZZ;
+                                 
+      /* Z * Z = ((x - y) * (x + y)) + (2.0 * x * y) * I */
+      /* calculate 1 - Z * Z */
+      __real__ ZZ = 1.0f - (x - y) * (x + y);
+      __imag__ ZZ = -2.0f * x * y;
+      ZZ = csqrtf (ZZ);
+
+
+      /* add  I * Z  to ZZ */
+
+      __real__ ZZ -= y;
+      __imag__ ZZ += x;
+
+      ZZ = clogf (ZZ);
+
+      /* mult by -I */
+      __real__ Res = __imag__ ZZ;
+      __imag__ Res = - __real__ ZZ;  
+    }
+  return (Res);
+}