pcg.h

#ifndef PCG_H
#define PCG_H

int pcg(int n, int (*atimes) (int, double *, double *, void *),
        int (*msolve) (int, double *, double *, int (*atimes)(int, double *, double *, void *), void *),
        double *x, double *b, double *r, double *z, double *p, int itmax,
    double eps, double *err, void *, double *valpha= 0, double *vbeta= 0);

#endif //PCG_H