initial cmath code and minor libm.h update

[libm] / src / cmath / cacos.c

diff --git a/src/cmath/cacos.c b/src/cmath/cacos.c
new file mode 100644 (file)
index 0000000..b8a2d71
--- /dev/null
+++ b/src/cmath/cacos.c
@@ -0,0 +1,52 @@
+/* origin: OpenBSD /usr/src/lib/libm/src/s_cacos.c */
+/*
+ * Copyright (c) 2008 Stephen L. Moshier <steve@moshier.net>
+ *
+ * Permission to use, copy, modify, and distribute this software for any
+ * purpose with or without fee is hereby granted, provided that the above
+ * copyright notice and this permission notice appear in all copies.
+ *
+ * THE SOFTWARE IS PROVIDED "AS IS" AND THE AUTHOR DISCLAIMS ALL WARRANTIES
+ * WITH REGARD TO THIS SOFTWARE INCLUDING ALL IMPLIED WARRANTIES OF
+ * MERCHANTABILITY AND FITNESS. IN NO EVENT SHALL THE AUTHOR BE LIABLE FOR
+ * ANY SPECIAL, DIRECT, INDIRECT, OR CONSEQUENTIAL DAMAGES OR ANY DAMAGES
+ * WHATSOEVER RESULTING FROM LOSS OF USE, DATA OR PROFITS, WHETHER IN AN
+ * ACTION OF CONTRACT, NEGLIGENCE OR OTHER TORTIOUS ACTION, ARISING OUT OF
+ * OR IN CONNECTION WITH THE USE OR PERFORMANCE OF THIS SOFTWARE.
+ */
+/*
+ *      Complex circular arc cosine
+ *
+ *
+ * SYNOPSIS:
+ *
+ * double complex cacos();
+ * double complex z, w;
+ *
+ * w = cacos (z);
+ *
+ *
+ * DESCRIPTION:
+ *
+ *
+ * w = arccos z  =  PI/2 - arcsin z.
+ *
+ *
+ * ACCURACY:
+ *
+ *                      Relative error:
+ * arithmetic   domain     # trials      peak         rms
+ *    DEC       -10,+10      5200      1.6e-15      2.8e-16
+ *    IEEE      -10,+10     30000      1.8e-14      2.2e-15
+ */
+
+#include "libm.h"
+
+double complex cacos(double complex z)
+{
+       double complex w;
+
+       w = casin(z);
+       w = (M_PI_2 - creal(w)) - cimag(w) * I;
+       return w;
+}