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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/polevl.c
parent22358dd7ce7bb49792204b698f01a6f69b9c8e08 (diff)
uClibc now has a math library. muahahahaha!
-Erik
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+/* 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 );
+}