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123 lines
3 KiB
C
123 lines
3 KiB
C
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/* polevl.c
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* p1evl.c
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*
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* Evaluate polynomial
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*
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*
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*
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* SYNOPSIS:
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*
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* int N;
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* double x, y, coef[N+1], polevl[];
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*
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* y = polevl( x, coef, N );
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*
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*
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*
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* DESCRIPTION:
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*
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* Evaluates polynomial of degree N:
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*
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* 2 N
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* y = C + C x + C x +...+ C x
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* 0 1 2 N
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*
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* Coefficients are stored in reverse order:
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*
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* coef[0] = C , ..., coef[N] = C .
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* N 0
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*
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* The function p1evl() assumes that coef[N] = 1.0 and is
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* omitted from the array. Its calling arguments are
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* otherwise the same as polevl().
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*
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*
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* SPEED:
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*
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* In the interest of speed, there are no checks for out
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* of bounds arithmetic. This routine is used by most of
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* the functions in the library. Depending on available
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* equipment features, the user may wish to rewrite the
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* program in microcode or assembly language.
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*
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*/
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/*
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Cephes Math Library Release 2.1: December, 1988
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Copyright 1984, 1987, 1988 by Stephen L. Moshier
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Redistribution and use in source and binary forms, with or without
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modification, are permitted provided that the following conditions are met:
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1. Redistributions of source code must retain the above copyright notice,
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this list of conditions and the following disclaimer.
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2. Redistributions in binary form must reproduce the above copyright
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notice, this list of conditions and the following disclaimer in the
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documentation and/or other materials provided with the distribution.
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3. Neither the name of the <ORGANIZATION> nor the names of its
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contributors may be used to endorse or promote products derived from
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this software without specific prior written permission.
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THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS "AS IS"
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AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
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IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE
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ARE DISCLAIMED. IN NO EVENT SHALL THE COPYRIGHT OWNER OR CONTRIBUTORS BE
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LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR
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CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF
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SUBSTITUTE GOODS OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS
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INTERRUPTION) HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN
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CONTRACT, STRICT LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE)
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ARISING IN ANY WAY OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE
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POSSIBILITY OF SUCH DAMAGE.
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Direct inquiries to 30 Frost Street, Cambridge, MA 02140
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*/
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double polevl( x, coef, N )
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double x;
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double coef[];
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int N;
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{
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double ans;
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int i;
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double *p;
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p = coef;
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ans = *p++;
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i = N;
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do
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ans = ans * x + *p++;
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while( --i );
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return( ans );
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}
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/* p1evl() */
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/* N
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* Evaluate polynomial when coefficient of x is 1.0.
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* Otherwise same as polevl.
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*/
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double p1evl( x, coef, N )
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double x;
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double coef[];
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int N;
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{
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double ans;
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double *p;
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int i;
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p = coef;
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ans = x + *p++;
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i = N-1;
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do
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ans = ans * x + *p++;
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while( --i );
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return( ans );
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}
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