1 files changed, 82 insertions, 0 deletions
diff --git a/winsup/mingw/mingwex/complex/cacos.c b/winsup/mingw/mingwex/complex/cacos.c
new file mode 100644
index 000000000..265cba0d7
--- /dev/null
+++ b/winsup/mingw/mingwex/complex/cacos.c
@@ -0,0 +1,82 @@
+/*
+   cacos.c
+   Contributed by Danny Smith
+   2003-10-20
+*/
+
+#include <math.h>
+#include <complex.h>
+
+#if 0
+/* cacos (Z) = -I * clog(Z + I * csqrt(1 - Z * Z)) */
+
+double complex cacos (double  complex Z)
+{
+  double complex Res;
+  double x, y;
+
+  x = __real__ Z;
+  y = __imag__ Z;
+
+  if (y == 0.0)
+    {
+      __real__ Res = acos (x);
+      __imag__ Res = 0.0;
+    }
+
+  else
+    {
+      double complex ZZ;
+      /* Z * Z = ((x - y) * (x + y)) + (2.0 * x * y) * I */
+      /* caculate 1 - Z * Z */
+      __real__ ZZ = 1.0 - (x - y) * (x + y);
+      __imag__ ZZ = -2.0 * x * y;
+
+       
+       Res = csqrt(ZZ);
+
+      /* calculate ZZ + I * sqrt (ZZ) */
+    
+      __real__ ZZ = x - __imag__ Res;
+      __imag__ ZZ = y + __real__ Res;
+       
+      ZZ = clog(ZZ);
+
+      /* mult by -I */
+
+      __real__ Res  =  __imag__ ZZ;
+      __imag__ Res = - __real__ ZZ;
+    }
+  return Res;
+}
+
+#else
+
+/* cacos ( Z ) =  pi/2 - casin ( Z ) */
+
+double complex cacos (double complex Z)
+{
+  double complex Res  = casin (Z);
+  __real__ Res = M_PI_2 - __real__ Res;
+  __imag__ Res = - __imag__ Res;
+  return Res;
+}
+#endif
+
+#if 0
+#include <stdio.h>
+int main()
+{
+  double z;
+  double complex bar = 0.7 + 1.2  * I;
+  double complex foo = cacos (bar);
+
+  printf ("%.16e\t%.16e\n", __real__ foo, __imag__ foo);
+
+  foo = cacos (bar);
+  printf ("%.16e\t%.16e\n", __real__ foo, __imag__ foo);
+
+  return 1;
+}
+#endif
+