initial cmath code and minor libm.h update

[libm] / src / cmath / cpow.c

diff --git a/src/cmath/cpow.c b/src/cmath/cpow.c
new file mode 100644 (file)
index 0000000..0bc36d3
--- /dev/null
+++ b/src/cmath/cpow.c
@@ -0,0 +1,61 @@
+/* origin: OpenBSD /usr/src/lib/libm/src/s_cpow.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 power function
+ *
+ *
+ * SYNOPSIS:
+ *
+ * double complex cpow();
+ * double complex a, z, w;
+ *
+ * w = cpow (a, z);
+ *
+ *
+ * DESCRIPTION:
+ *
+ * Raises complex A to the complex Zth power.
+ * Definition is per AMS55 # 4.2.8,
+ * analytically equivalent to cpow(a,z) = cexp(z clog(a)).
+ *
+ * ACCURACY:
+ *
+ *                      Relative error:
+ * arithmetic   domain     # trials      peak         rms
+ *    IEEE      -10,+10     30000       9.4e-15     1.5e-15
+ */
+
+#include "libm.h"
+
+double complex cpow(double complex a, double complex z)
+{
+       double x, y, r, theta, absa, arga;
+
+       x = creal(z);
+       y = cimag(z);
+       absa = cabs(a);
+       if (absa == 0.0)
+               return 0.0;
+       arga = carg(a);
+       r = pow(absa, x);
+       theta = x * arga;
+       if (y != 0.0) {
+               r = r * exp(-y * arga);
+               theta += y * log(absa);
+       }
+       return cpack(r * cos(theta), (r * sin(theta)));
+}