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Diffstat (limited to 'libm/double/chbevl.c')
-rw-r--r-- | libm/double/chbevl.c | 82 |
1 files changed, 0 insertions, 82 deletions
diff --git a/libm/double/chbevl.c b/libm/double/chbevl.c deleted file mode 100644 index 539388164..000000000 --- a/libm/double/chbevl.c +++ /dev/null @@ -1,82 +0,0 @@ -/* chbevl.c - * - * Evaluate Chebyshev series - * - * - * - * SYNOPSIS: - * - * int N; - * double x, y, coef[N], chebevl(); - * - * y = chbevl( x, coef, N ); - * - * - * - * DESCRIPTION: - * - * Evaluates the series - * - * N-1 - * - ' - * y = > coef[i] T (x/2) - * - i - * i=0 - * - * of Chebyshev polynomials Ti at argument x/2. - * - * Coefficients are stored in reverse order, i.e. the zero - * order term is last in the array. Note N is the number of - * coefficients, not the order. - * - * If coefficients are for the interval a to b, x must - * have been transformed to x -> 2(2x - b - a)/(b-a) before - * entering the routine. This maps x from (a, b) to (-1, 1), - * over which the Chebyshev polynomials are defined. - * - * If the coefficients are for the inverted interval, in - * which (a, b) is mapped to (1/b, 1/a), the transformation - * required is x -> 2(2ab/x - b - a)/(b-a). If b is infinity, - * this becomes x -> 4a/x - 1. - * - * - * - * SPEED: - * - * Taking advantage of the recurrence properties of the - * Chebyshev polynomials, the routine requires one more - * addition per loop than evaluating a nested polynomial of - * the same degree. - * - */ -/* chbevl.c */ - -/* -Cephes Math Library Release 2.0: April, 1987 -Copyright 1985, 1987 by Stephen L. Moshier -Direct inquiries to 30 Frost Street, Cambridge, MA 02140 -*/ - -double chbevl( x, array, n ) -double x; -double array[]; -int n; -{ -double b0, b1, b2, *p; -int i; - -p = array; -b0 = *p++; -b1 = 0.0; -i = n - 1; - -do - { - b2 = b1; - b1 = b0; - b0 = x * b1 - b2 + *p++; - } -while( --i ); - -return( 0.5*(b0-b2) ); -} |