double polint3(double x, int n, double *xa, double *ya) { int shift=leftX(n, xa, x); double ar; ar=polintN(x,3,xa+shift, ya+shift); if(shift==0) return ar; shift--; return 0.5*( ar+ polintN(x,3,xa+shift, ya+shift)); }
static double polint4(double x, int n, double *xa, double *ya) { int shift=leftX4(n, xa, x); return polintN(x,4,xa+shift, ya+shift); }
double polint2(double x, int n, double *xa, double *ya) { int shift=leftXN(2,n, xa, x); return polintN(x,2,xa+shift, ya+shift); }