问在C中使用递归函数时避免使用全局变量

EN

gcc NDimensionalInterpolation.c -o NDimensionalInterpolation -Wall -lm

#include <stdio.h>
#include <stdlib.h>
#include <math.h>

int linearInterpolation(double *, double **, double *, int);
double ** allocateDoubleMatrix(int, int);
double * allocateDoubleVector(int);
void interp(int, int, double *, double *, double *);
double mult(int, double, double *, double *);

/* The objectionable global 
variables that I want to get rid of! */

int iter=0;
double fxInterpolated=0;

int main(int argc, char *argv[]){

 double *fx, **a, *x;
 int dims=2;

 x=allocateDoubleVector(dims);
 a=allocateDoubleMatrix(dims,2);
 fx=allocateDoubleVector(dims*2);

 x[0]=0.25;
 x[1]=0.4;

 a[0][0]=0;
 a[0][1]=1;
 a[1][0]=0;
 a[1][1]=1;

 fx[0]=1;
 fx[1]=3;
 fx[2]=2;
 fx[3]=4;
 linearInterpolation(fx, a, x, dims);
 printf("%f\n",fxInterpolated);

 return (EXIT_SUCCESS);

 } 

 int linearInterpolation(double *fx, double **a, double *x, int dims){

  double *b, *pos;
  int i;

  b=allocateDoubleVector(dims);
  pos=allocateDoubleVector(dims);

  for (i=0; i<dims;i++)
   b[i] = (x[i] - a[i][0]) / (a[i][1] -  a[i][0]);

  interp(0,dims,pos,fx,b); 

  return (EXIT_SUCCESS);

}  

void interp(int j, int dims, double *pos, double *fx, double *b) {

int i;

if (j == dims){
  fxInterpolated+=mult(dims,fx[iter],pos,b);
  iter++;
  return;
}

 for (i = 0; i < 2; i++){
   pos[j]=(double)i; 
   interp(j+1,dims,pos,fx,b);
 }

}

double mult(int dims, double fx, double *pos, double *b){

 int i;
 double val=1.0; 

 for (i = 0; i < dims; i++){
  val *= fabs(1.0-pos[i]-b[i]); 
 } 
 val *= fx;

 printf("mult val= %f fx=%f\n",val, fx);
 return val;

}

double ** allocateDoubleMatrix(int i, int j){

 int k;
 double ** matrix;
 matrix = (double **) calloc(i, sizeof(double *));
 for (k=0; k< i; k++)matrix[k] = allocateDoubleVector(j);
 return matrix;
}

 double * allocateDoubleVector(int i){
  double *vector;
  vector = (double *) calloc(i,sizeof(double));
  return vector;
}

void interp(int j, int dims, double *pos, double *fx, double *b, int *iter) {

int i;

if (j == dims){
fxInterpolated+=mult(dims,fx[*iter],pos,b);
*iter++;
return; 
}

 for (i = 0; i < 2; i++){
  pos[j]=(double)i; 
  interp(j+1,dims,pos,fx,b,iter);
 }