poly.c

#include<stdio.h>
#include<math.h>
#define MAX 20
#define COMPARE(x,y) (((x)==(y))?0:((x)>(y))?1:-1)
typedef struct
{
    float coeff;
    int exp;
}POLY;

POLY terms[MAX];
int startA=0, finishA, startB, finishB, startD, finishD, avail=0;

void input_poly(int f, int *p)
{
    int i;
    printf("Enter the number of terms for polynomial: ");
    scanf("%d",p);

    (*p)--;

    for(i=f;i<=(*p+f);i++)
    {
     printf("Enter Coefficient and Exponent: ");
     scanf("%f%d",&terms[i].coeff,&terms[i].exp);
    }

    printf("\n\n");
    //p=NULL;
}

void disp_poly(int f,int l)
{
    int i;

    for(i=f;i<=l;i++)
    {
     if(terms[i].exp)
      printf("+%.0fX^%d",terms[i].coeff,terms[i].exp);
     else
      printf("+%.0f",terms[i].coeff);
    }
     printf("\n\n");
}

void attach(float c, int e)
{
    terms[avail].coeff = c;
    terms[avail].exp   = e;
    avail++;
}

void poly_add(int startA, int startB, int finishA, int finishB, int *startD, int *finishD)
{
    float c;
    *startD = avail;
    while(startA <= finishA && startB <= finishB )
    {
     switch(COMPARE(terms[startA].exp,terms[startB].exp))
     {

      case -1: attach( terms[startB].coeff , terms[startB].exp );
           startB++;
           break;

      case  0: c=terms[startA].coeff+terms[startB].coeff;
           if(c!=0)
           attach( c , terms[startA].exp );
           startA++;
           startB++;
           break;

      case  1: attach( terms[startA].coeff , terms[startA].exp );
           startA++;
           break;

     }
    }

    *finishD = avail-1;
}

void poly_eval(float x,int n)
{
    int i;
    float val=0;

    for(i=0;i<=n;i++)
    val += terms[i].coeff * pow(x , terms[i].exp);

    printf("Value= %.0f\n",val);
}

void main()
{
    int c;
    float x;
    printf("Menu:\n\t1. Addition of two polynomials\n\t2. Evaluation of a polynomial\nEnter your choice: ");
    scanf("%d",&c);
    printf("\n\n");
    switch(c)
    {
     case  1 :
           input_poly(startA,&finishA);
           startB=finishA+1;
           input_poly(startB,&finishB);
           finishB+=startB;
           avail = finishB+1;

           poly_add(startA,startB,finishA,finishB,&startD,&finishD);
           printf("First  polynomial is: ");    disp_poly(startA,finishA);
           printf("Second polynomial is: ");    disp_poly(startB,finishB);
           printf("Addition of two polynomials is:\n");
           disp_poly(startD,finishD);
           break;

     case  2 : input_poly(startA,&finishA);
           disp_poly(startA,finishA);
           printf("Enter the value of X: ");
           scanf("%f",&x);
           poly_eval(x,finishA);
           break;

     default : printf("Invalid case\n");
    }
}