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authorEric Andersen <andersen@codepoet.org>2001-05-10 00:40:28 +0000
committerEric Andersen <andersen@codepoet.org>2001-05-10 00:40:28 +0000
commit1077fa4d772832f77a677ce7fb7c2d513b959e3f (patch)
tree579bee13fb0b58d2800206366ec2caecbb15f3fc /libm/double/round.c
parent22358dd7ce7bb49792204b698f01a6f69b9c8e08 (diff)
uClibc now has a math library. muahahahaha!
-Erik
Diffstat (limited to 'libm/double/round.c')
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+/* round.c
+ *
+ * Round double to nearest or even integer valued double
+ *
+ *
+ *
+ * SYNOPSIS:
+ *
+ * double x, y, round();
+ *
+ * y = round(x);
+ *
+ *
+ *
+ * DESCRIPTION:
+ *
+ * Returns the nearest integer to x as a double precision
+ * floating point result. If x ends in 0.5 exactly, the
+ * nearest even integer is chosen.
+ *
+ *
+ *
+ * ACCURACY:
+ *
+ * If x is greater than 1/(2*MACHEP), its closest machine
+ * representation is already an integer, so rounding does
+ * not change it.
+ */
+
+/*
+Cephes Math Library Release 2.1: January, 1989
+Copyright 1984, 1987, 1989 by Stephen L. Moshier
+Direct inquiries to 30 Frost Street, Cambridge, MA 02140
+*/
+#include <math.h>
+#ifdef ANSIPROT
+double floor ( double );
+#else
+double floor();
+#endif
+
+double round(x)
+double x;
+{
+double y, r;
+
+/* Largest integer <= x */
+y = floor(x);
+
+/* Fractional part */
+r = x - y;
+
+/* Round up to nearest. */
+if( r > 0.5 )
+ goto rndup;
+
+/* Round to even */
+if( r == 0.5 )
+ {
+ r = y - 2.0 * floor( 0.5 * y );
+ if( r == 1.0 )
+ {
+rndup:
+ y += 1.0;
+ }
+ }
+
+/* Else round down. */
+return(y);
+}