Lagrangian Interpolation

#include<stdio.h>
#include<malloc.h>
#include<stdlib.h>
FILE *fp;
int main(int argc, char *argv[])
{
double **A,*b,*xn,*xnplus1,*p,temp=1.0,x,value=0.0,**U;
int ROW,i,j,k,t=1;
char ch;
if(argc==1)
    {
    printf("\n Enter the number of values:");
    scanf("%d",&ROW);
    printf("\n Enter the value at which value has to be aprroximated:");
    scanf("%lf",&x);
    A=(double **)malloc((ROW+1)*sizeof(double*));
    for(i=0;i<=ROW;i++)
        {
        A[i]=(double *)malloc((ROW+1)*sizeof(double));
        }
    b=(double *)malloc((ROW+1)*sizeof(double));
    p=(double *)malloc((ROW+1)*sizeof(double));
    xn=(double *)malloc((ROW+1)*sizeof(double));
    xnplus1=(double *)malloc((ROW+1)*sizeof(double));
    for(i=1;i<=ROW;i++)
        {
        printf("\n Enter the value of X[%d]:",i);
        scanf("%lf",&A[i][1]);
        }
    for(i=1;i<=ROW;i++)
        {
        printf("\n Enter the value of Y[%d]:",i);
        scanf("%lf",&A[i][2]);
        }
       
    }
else if (argc==2)
    {
    fp=fopen(argv[1],"r");
        if(fp==NULL)
            {
            printf("\n File not found, program will terminate:");
            exit(0);
            }
    fscanf(fp,"%d",&ROW);
    fscanf(fp,"%lf",&x);
    A=(double **)malloc((ROW+1)*sizeof(double*));
    for(i=0;i<=ROW;i++)
        {
        A[i]=(double *)malloc((ROW+1)*sizeof(double));
        }
    b=(double *)malloc((ROW+1)*sizeof(double));
    p=(double *)malloc((ROW+1)*sizeof(double));
    xn=(double *)malloc((ROW+1)*sizeof(double));
    while(!feof(fp))
    {
    for(i=1;i<=ROW;i++)
    {
        for(j=1;j<=2;j++)
        {
        fscanf(fp,"%lf ",&A[i][j]);
        }
       
    }
    }
    fclose(fp);
    }
    else
    {
    printf("\n Invalid Arguments,program will terminate:\n");
    exit(0);
    }
printf("\n         X          Y");
printf("\n------------------------------------------------------------------\n");
for(i=1;i<=ROW;i++)
    {
    for(j=1;j<=2;j++)
        {
       
        A[i][j];
        printf("   %+lf",A[i][j]);
        }
    printf("\n");
    }
printf("\n------------------------------------------------------------------\n");
for(i=1;i<=ROW;i++)
    {
     for(j=1;j<=ROW;j++)
         {
         if(i==j)
             continue;
         else
             temp = temp * ((x-A[j][1])/(A[i][1]-A[j][1]));
         }
     //xn[i]=temp;
     value += temp*A[i][2];
     //printf("\n ------------------------------->%lf",temp);   
     temp=1.0;
    }   
printf("\n Value at %+lf by Lagrangian Interpolation formula is %+lf\n",x,value);
return 0;
}