qpms/kahansum.h

   1 /*! \file kahansum.h
   2  * \brief Inline functions providing Kahan summation.
   3  */
   4 #ifndef KAHANSUM_H
   5 #define KAHANSUM_H
   6
   7 #include <complex.h>
   8
   9 static inline void kahaninit(double * const sum, double * const compensation) {
  10         *sum = 0;
  11         *compensation = 0;
  12 }
  13
  14 static inline void kahanadd(double *sum, double *compensation, double input) {
  15         double compensated_input = input - *compensation;
  16         double nsum = *sum + compensated_input;
  17         *compensation = (nsum - *sum) - compensated_input;
  18         *sum = nsum;
  19 }
  20
  21
  22 static inline void ckahaninit(complex double * const sum, complex double * const compensation) {
  23         *sum = 0;
  24         *compensation = 0;
  25 }
  26
  27 static inline void ckahanadd(complex double *sum, complex double *compensation, complex double input) {
  28         complex double compensated_input = input - *compensation;
  29         complex double nsum = *sum + compensated_input;
  30         *compensation = (nsum - *sum) - compensated_input;
  31         *sum = nsum;
  32 }
  33
  34 #endif //KAHANSUM_H