This is the program to solve polynomial equations using bisection method

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C

#include<stdio.h>
#include<math.h>
#include<stdlib.h>
void bisect(float *p,int n,int a);
float value(float *p,int n,int a);
int main()
{
    int a,i;
    float *p;
    printf("enter the degree of the polynomial\n");
    scanf("%d",&a);
    p=(float *) malloc(a*sizeof(float));
    for(i=0;i<=a;i++)
    {
        printf("enter the coefficient of x^%d\n",i);
        scanf("%f",p+i);
    }
    for(i=-100;i<100;i++)
    {


        if(value(p,i,a)*value(p,i+1,a)<0)
        {
            bisect(p,i,a);
        }
    }
    return 0;
}
float value(float *p,int n,int a)
{
    float sum=0;
    int i;
    for(i=0;i<=a;i++)
    {
        sum=sum+*(p+i)*pow(n,i);
    }
    return sum;
}
void bisect(float *p,int n,int a)
{
    float j,k,l;
    int i;
    j=n;k=n+1;l=(j+k)/2;
    for(i=0;i<50;i++)
    {
        if(value(p,j,a)*value(p,l,a)<0)
        {
            j=j;k=l;l=(j+k)/2;
        }
       else if(value(p,l,a)*value(p,k,a)<0)
       {
           l=(l+k)/2;j=l;
       }
    }
    printf("the root of the equation is %f\n",l);
}

This is done by using bisection method, and i know that the code isn't optimized , i am unable to derive any root from my algorithm though, i want to find out any logical errors as i could find none after much investigation. I would like to know if there is any fault with the equating of data types. thanks in advance.