#include <stdio.h>
#include <stdlib.h>
#define N 100
double min=-100, max=100;

void PrintVect(double B[],int n){
  int i;
  for (i=0;i<n;i++) printf("x[%d]=%lf\n", i,B[i]);
}

double Rand(double min, double max){
  return min+(max-min)*rand()/RAND_MAX;
}

void PrintMatr(double A[][N], int n, int m){
  int i,j;
  for(i=0;i<m;i++){
    for(j=0;j<n;j++) printf("%lf\t",A[i][j]);
    printf("\n");
  }

}

void InitTridiag(double A[][N], int n){
  int i,j;
  i=0;
  for(i=0;i<n;i++){
    for(j=0;j<n;j++){
      if(j>=i-1 && j<=i+1) A[i][j]=Rand(min,max);else A[i][j]=0;
    }
  }
}

void Solve(double A[N][N], double B[N], double x[N], int n){
  int i;
  double l[n-1],m[n-1];
  double c;
  l[0]=B[0]/A[0][0];
  m[0]=-A[0][1]/A[0][0];
  for(i=1;i<n-1;i++){
    c=A[i][i]+A[i][i-1]*m[i-1];
    l[i]=(B[i]-A[i][i-1]*l[i-1])/c;
    m[i]=-A[i][i+1]/c;
  }
  i=n-1;
  c=A[i][i]+A[i][i-1]*m[i-1];
  x[i]=(B[i]-A[i][i-1]*l[i-1])/c;

  for(i=n-2;i>=0;i--){
    x[i]=l[i]+m[i]*x[i+1];
  }
}

int main() {
  double A[N][N],B[N],x[N];
  int n=5, i;
  for(i=0;i<n;i++){
    B[i]=i;
  }
  InitTridiag(A,n);
  PrintMatr(A,n,n);
  Solve(A,B,x,n);
  PrintVect(x,n);
}