Argthtjtr

f(t)={t+3: t ∈[0,T].

0: otherwise}

1. Read in an integer value for T. Sample the function f(t) above, at t = 0, 1, 2 . . . T and write the values to a file ‘function.txt’.




2. Read the values from the file, and place them in an array.




3. Write a function called “convolution” which takes two arrays as arguments, calculates their discrete convolution and prints out the resulting function in two columns: index and convolution. Print the output both to the screen and to a file called ‘convolution.txt’. Your function should only do the calculation for indices corresponding to non-zero values of the convolution. Assume both functions are only nonzero between 0 and T. (hint: the convolution will only be nonzero between 0 and 2T- make sure you understand why.)



4. 
   

   Call your function with both functions f and g given by the same array from part 1.
   The formula for finding the convolution is

   
   
   

   (f*g)[n] ∑ (f[m] g[n-m])

   
   

This is what I have so far. need help finishing it.

#include <stdlib.h>

#include <stdio.h>

void convolution (int F[ ] ,int G [ ])

{



    FILE *fptr;

    int i,j,T;

    int x;

    F[T],G[T];

    x= T+1;

    fptr = fopen("function.txt","r");

    if (fptr == NULL)

    {

        printf("No such file!");

        exit(0);

    }

    for (i=0; i<=x; i++)

    {

        F[i]= i+3;

        fscanf(fptr,"%d",&j);

        printf("F[%d] = %dn",i,F[i]);

    }

    printf("n");

    fclose(fptr);

    int sum;

    for (c=0; c<2T+1; c++)

    {

       sum =0; g=c;

       for(f=0; f<c; f++,g--)

       {

            if (f<=T && g<=T)

            {

                 sum = sum + F [ ]* G [ ];

            }

            printf("convolution [%d] = %d",c, sum);

       }

    }

}



int main (void)

{

    int x;

    int T,F[x],G[x];

    x= T+1;

    printf("Enter the value of T: ");

    scanf("%d",&T);

    convolution(F,G);

    return 0;

 }

You have a bit of a mess in your variale declarations:

int main (void)

{

    int x;

    int T,F[x],G[x];    <==== x is not initialized. You define arrays of random length. Might be 0.

    x= T+1;             <==== T is not initialized.

    printf("Enter the value of T: ");

    scanf("%d",&T);     <==== now T has a value but it is never used.

    convolution(F,G);

    return 0;

}

Then in the called function the same problems are repeated:

void convolution (int F[ ] ,int G [ ])

{

    FILE *fptr;

    int i,j,T;

    int x;

    F[T],G[T];   <=== T is not initialized; You access random elements of arrays of unknown random length.

    x= T+1;      <=== T is still not initialized.

Then desaster accelarates... ;)

for (i=0; i<=x; i++)  <== x is T+1 (still uninitialized) 

{

    F[i]= i+3;   <== With i going up to x which is T+1 you access index T+1 of an array of size [T] which is out of bounds.

    fscanf(fptr,"%d",&j);

    printf("F[%d] = %dn",i,F[i]);

}

You should start all over with your variables.

There are many uninitialized variables in your code. Reading them before writing into them causes undefined behavior.

For example, in main the variable x is uninitialized. You are using it for defining variable length arrays F[x] and G[x].

In the convolution function the vairiable T is uninitialized. And you are using its value in the statement x= T+1;
This is undefined behavior. See this question and its answers for the reason.

And even if the initial value of T happens to be 0, then the inner for loop will not be reached as the value of c cannot exceed 1.