summaryrefslogtreecommitdiff
path: root/newlib/libm/math/w_atan2.c
diff options
context:
space:
mode:
Diffstat (limited to 'newlib/libm/math/w_atan2.c')
-rw-r--r--newlib/libm/math/w_atan2.c117
1 files changed, 117 insertions, 0 deletions
diff --git a/newlib/libm/math/w_atan2.c b/newlib/libm/math/w_atan2.c
new file mode 100644
index 00000000000..91742c72b91
--- /dev/null
+++ b/newlib/libm/math/w_atan2.c
@@ -0,0 +1,117 @@
+
+/* @(#)w_atan2.c 5.1 93/09/24 */
+/*
+ * ====================================================
+ * Copyright (C) 1993 by Sun Microsystems, Inc. All rights reserved.
+ *
+ * Developed at SunPro, a Sun Microsystems, Inc. business.
+ * Permission to use, copy, modify, and distribute this
+ * software is freely granted, provided that this notice
+ * is preserved.
+ * ====================================================
+ *
+ */
+
+/*
+FUNCTION
+ <<atan2>>, <<atan2f>>---arc tangent of y/x
+
+INDEX
+ atan2
+INDEX
+ atan2f
+
+ANSI_SYNOPSIS
+ #include <math.h>
+ double atan2(double <[y]>,double <[x]>);
+ float atan2f(float <[y]>,float <[x]>);
+
+TRAD_SYNOPSIS
+ #include <math.h>
+ double atan2(<[y]>,<[x]>);
+ double <[y]>;
+ double <[x]>;
+
+ float atan2f(<[y]>,<[x]>);
+ float <[y]>;
+ float <[x]>;
+
+DESCRIPTION
+
+<<atan2>> computes the inverse tangent (arc tangent) of <[y]>/<[x]>.
+<<atan2>> produces the correct result even for angles near
+@ifinfo
+pi/2 or -pi/2
+@end ifinfo
+@tex
+$\pi/2$ or $-\pi/2$
+@end tex
+(that is, when <[x]> is near 0).
+
+<<atan2f>> is identical to <<atan2>>, save that it takes and returns
+<<float>>.
+
+RETURNS
+<<atan2>> and <<atan2f>> return a value in radians, in the range of
+@ifinfo
+-pi to pi.
+@end ifinfo
+@tex
+$-\pi$ to $\pi$.
+@end tex
+
+If both <[x]> and <[y]> are 0.0, <<atan2>> causes a <<DOMAIN>> error.
+
+You can modify error handling for these functions using <<matherr>>.
+
+PORTABILITY
+<<atan2>> is ANSI C. <<atan2f>> is an extension.
+
+
+*/
+
+/*
+ * wrapper atan2(y,x)
+ */
+
+#include "fdlibm.h"
+#include <errno.h>
+
+#ifndef _DOUBLE_IS_32BITS
+
+#ifdef __STDC__
+ double atan2(double y, double x) /* wrapper atan2 */
+#else
+ double atan2(y,x) /* wrapper atan2 */
+ double y,x;
+#endif
+{
+#ifdef _IEEE_LIBM
+ return __ieee754_atan2(y,x);
+#else
+ double z;
+ struct exception exc;
+ z = __ieee754_atan2(y,x);
+ if(_LIB_VERSION == _IEEE_||isnan(x)||isnan(y)) return z;
+ if(x==0.0&&y==0.0) {
+ /* atan2(+-0,+-0) */
+ exc.arg1 = y;
+ exc.arg2 = x;
+ exc.type = DOMAIN;
+ exc.name = "atan2";
+ exc.err = 0;
+ exc.retval = 0.0;
+ if(_LIB_VERSION == _POSIX_)
+ errno = EDOM;
+ else if (!matherr(&exc)) {
+ errno = EDOM;
+ }
+ if (exc.err != 0)
+ errno = exc.err;
+ return exc.retval;
+ } else
+ return z;
+#endif
+}
+
+#endif /* defined(_DOUBLE_IS_32BITS) */