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Diffstat (limited to 'libm/double/polevl.c')
-rw-r--r-- | libm/double/polevl.c | 97 |
1 files changed, 97 insertions, 0 deletions
diff --git a/libm/double/polevl.c b/libm/double/polevl.c new file mode 100644 index 000000000..4d050fbfc --- /dev/null +++ b/libm/double/polevl.c @@ -0,0 +1,97 @@ +/* polevl.c + * p1evl.c + * + * Evaluate polynomial + * + * + * + * SYNOPSIS: + * + * int N; + * double x, y, coef[N+1], polevl[]; + * + * y = polevl( x, coef, N ); + * + * + * + * DESCRIPTION: + * + * Evaluates polynomial of degree N: + * + * 2 N + * y = C + C x + C x +...+ C x + * 0 1 2 N + * + * Coefficients are stored in reverse order: + * + * coef[0] = C , ..., coef[N] = C . + * N 0 + * + * The function p1evl() assumes that coef[N] = 1.0 and is + * omitted from the array. Its calling arguments are + * otherwise the same as polevl(). + * + * + * SPEED: + * + * In the interest of speed, there are no checks for out + * of bounds arithmetic. This routine is used by most of + * the functions in the library. Depending on available + * equipment features, the user may wish to rewrite the + * program in microcode or assembly language. + * + */ + + +/* +Cephes Math Library Release 2.1: December, 1988 +Copyright 1984, 1987, 1988 by Stephen L. Moshier +Direct inquiries to 30 Frost Street, Cambridge, MA 02140 +*/ + + +double polevl( x, coef, N ) +double x; +double coef[]; +int N; +{ +double ans; +int i; +double *p; + +p = coef; +ans = *p++; +i = N; + +do + ans = ans * x + *p++; +while( --i ); + +return( ans ); +} + +/* p1evl() */ +/* N + * Evaluate polynomial when coefficient of x is 1.0. + * Otherwise same as polevl. + */ + +double p1evl( x, coef, N ) +double x; +double coef[]; +int N; +{ +double ans; +double *p; +int i; + +p = coef; +ans = x + *p++; +i = N-1; + +do + ans = ans * x + *p++; +while( --i ); + +return( ans ); +} |