diff options
author | Eric Andersen <andersen@codepoet.org> | 2001-05-10 00:40:28 +0000 |
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committer | Eric Andersen <andersen@codepoet.org> | 2001-05-10 00:40:28 +0000 |
commit | 1077fa4d772832f77a677ce7fb7c2d513b959e3f (patch) | |
tree | 579bee13fb0b58d2800206366ec2caecbb15f3fc /libm/double/round.c | |
parent | 22358dd7ce7bb49792204b698f01a6f69b9c8e08 (diff) |
uClibc now has a math library. muahahahaha!
-Erik
Diffstat (limited to 'libm/double/round.c')
-rw-r--r-- | libm/double/round.c | 70 |
1 files changed, 70 insertions, 0 deletions
diff --git a/libm/double/round.c b/libm/double/round.c new file mode 100644 index 000000000..df4564a0f --- /dev/null +++ b/libm/double/round.c @@ -0,0 +1,70 @@ +/* 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); +} |