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+/* $NetBSD: ctan.c,v 1.1 2007/08/20 16:01:37 drochner Exp $ */
+
+/*-
+ * Copyright (c) 2007 The NetBSD Foundation, Inc.
+ * All rights reserved.
+ *
+ * This code is derived from software written by Stephen L. Moshier.
+ * It is redistributed by the NetBSD Foundation by permission of the author.
+ *
+ * Redistribution and use in source and binary forms, with or without
+ * modification, are permitted provided that the following conditions
+ * are met:
+ * 1. Redistributions of source code must retain the above copyright
+ * notice, this list of conditions and the following disclaimer.
+ * 2. Redistributions in binary form must reproduce the above copyright
+ * notice, this list of conditions and the following disclaimer in the
+ * documentation and/or other materials provided with the distribution.
+ *
+ * THIS SOFTWARE IS PROVIDED BY THE NETBSD FOUNDATION, INC. AND CONTRIBUTORS
+ * ``AS IS'' AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED
+ * TO, THE IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR
+ * PURPOSE ARE DISCLAIMED. IN NO EVENT SHALL THE FOUNDATION OR CONTRIBUTORS
+ * BE LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR
+ * CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF
+ * SUBSTITUTE GOODS OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS
+ * INTERRUPTION) HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN
+ * CONTRACT, STRICT LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE)
+ * ARISING IN ANY WAY OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE
+ * POSSIBILITY OF SUCH DAMAGE.
+ *
+ * imported and modified include for newlib 2010/10/03
+ * Marco Atzeri <marco_atzeri@yahoo.it>
+ */
+
+/*
+FUNCTION
+ <<ctan>>, <<ctanf>>---complex tangent
+
+INDEX
+ ctan
+INDEX
+ ctanf
+
+ANSI_SYNOPSIS
+ #include <complex.h>
+ double complex ctan(double complex <[z]>);
+ float complex ctanf(float complex <[z]>);
+
+
+DESCRIPTION
+ These functions compute the complex tangent of <[z]>.
+
+ <<ctanf>> is identical to <<ctan>>, except that it performs
+ its calculations on <<floats complex>>.
+
+RETURNS
+ These functions return the complex tangent value.
+
+PORTABILITY
+ <<ctan>> and <<ctanf>> are ISO C99
+
+QUICKREF
+ <<ctan>> and <<ctanf>> are ISO C99
+
+*/
+
+
+#include <complex.h>
+#include <math.h>
+#include "cephes_subr.h"
+
+double complex
+ctan(double complex z)
+{
+ double complex w;
+ double d;
+
+ d = cos(2.0 * creal(z)) + cosh(2.0 * cimag(z));
+
+ if (fabs(d) < 0.25)
+ d = __mlibc_ctans(z);
+
+ if (d == 0.0) {
+ /* mtherr ("ctan", OVERFLOW); */
+ w = HUGE_VAL + HUGE_VAL * I;
+ return w;
+ }
+
+ w = sin(2.0 * creal(z)) / d + (sinh(2.0 * cimag(z)) / d) * I;
+ return w;
+}