Initial revision

From-SVN: r26263

libjava/java/lang/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) */