#include #include #define N 4 /* tridiag.c : 1999 3 8 by Oguni */ main(){ double a[N][3]={0.,3.,-1.,-1.,3.,-1.,-1.,3.,-1.,-1.,3.,0.}; double b[N]={2.,1.,1.,2.}; double x[N], tol=0.000001; int i,j,n=4; for (i=0; i=tol) a[i][2]=a[i][2]/a[i][1]; } a[n-1][1]=1.0-a[n-1][0]*a[n-2][2]; y[0]=b[0]; for (i=1; i=0; i--) {x[i]=y[i]-a[i][2]*x[i+1];} return; }