WDL/cmath/horner.h

   1 /*
   2   horner.h
   3   Copyright (C) 2011 and later Lubomir I. Ivanov (neolit123 [at] gmail)
   4
   5   This software is provided 'as-is', without any express or implied
   6   warranty.  In no event will the authors be held liable for any damages
   7   arising from the use of this software.
   8
   9   Permission is granted to anyone to use this software for any purpose,
  10   including commercial applications, and to alter it and redistribute it
  11   freely, subject to the following restrictions:
  12
  13   1. The origin of this software must not be misrepresented; you must not
  14      claim that you wrote the original software. If you use this software
  15      in a product, an acknowledgment in the product documentation would be
  16      appreciated but is not required.
  17   2. Altered source versions must be plainly marked as such, and must not be
  18      misrepresented as being the original software.
  19   3. This notice may not be removed or altered from any source distribution.
  20 */
  21
  22 /*
  23   algorithm to evaluate integer order polynomials using horner's scheme.
  24 */
  25
  26 #ifndef _HORNER_H_
  27 #define _HORNER_H_
  28
  29 #include "custom_math.h"
  30 #include "complex_number.h"
  31
  32 /* settings */
  33 #ifndef _HORNER_INLINE
  34   #define _HORNER_INLINE _CMATH_INLINE
  35 #else
  36   #define _HORNER_INLINE
  37 #endif
  38
  39 /* real */
  40 _HORNER_INLINE
  41 cmath_t horner_eval
  42 (const cmath_t *coeff, const cmath_t x, cmath_uint16_t order)
  43 {
  44   register cmath_t y = coeff[0];
  45   register cmath_uint16_t n = 1;
  46   order += 1;
  47   while(n < order)
  48   {
  49     y = y*x + coeff[n];
  50     n++;
  51   }
  52   return y;
  53 }
  54
  55 /* complex */
  56 _HORNER_INLINE
  57 cnum_s horner_eval_c
  58 (const cnum_s *coeff, const cnum_s x, cmath_uint16_t order)
  59 {
  60   register cmath_uint16_t n = 1;
  61   cnum_s y = coeff[0];
  62   order += 1;
  63   while(n < order)
  64   {
  65     y = cnum_add(cnum_mul(y, x), coeff[n]);
  66     n++;
  67   }
  68   return y;
  69 }
  70
  71 #endif /* _HORNER_H_ */