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/* polynomial arithmetic */
/*
/* array-representation polynomial manipulation for Mathpert
M. Beeson
Original date 3.19.91
1.29.98 last modified
*/

#include <assert.h>
#include <math.h>
#define POLYVAL_DLL
#include "globals.h"
#include "polynoms.h"
#include "deval.h"
#include "evalpoly.h"

MEXPORT_POLYVAL term evalpoly(POLYnomial c, term a)
/* return p(a).  It is not presumed that a is seminumerical although
in applications it often is.  The coefficients are simplified using
polyval. */

{ int j;
  term temp;
  unsigned short n = ARITY(c) - 1;  /* degree of c */
  term p = ARG(n,c);
  for(j=n-1;j>=0;j--)
     { polyval(sum(product(p,a),ARG(j,c)),&temp);
       p = temp;
     }
  return p;
}
/*___________________________________________________________________________*/
MEXPORT_POLYVAL int devalpoly(POLYnomial c, double a, double *ans)
/* Put p(a) in *ans, returning 0 for success.
Return 1 if deval fails.  Watch out for overflow.
*/

{ int j;
  double p,z;
  unsigned short n = ARITY(c) - 1;  /* degree of c */
  int exponent,exponent2;
  static int maxexp;
  deval(ARG(n,c),&p);
  if(p == BADVAL)
     return 1;
  for(j=n-1;j>=0;j--)
     { deval(ARG(j,c),&z);
       frexp(p,&exponent);
       frexp(a,&exponent2);
       if(maxexp == 0)
          frexp(BADVAL,&maxexp);
       if(fabs(exponent + exponent2) > maxexp)
          return 1;
       p = p*a+z;
       if(fabs(p) > BADVAL)
          return 1;
     }
  *ans = p;
  return 0;
}