a) modify the program to use pointers to access the array elements. b) move the

ID: 645731 • Letter: A

Question

a) modify the program to use pointers to access the array elements.

b) move the calculation of average, variance and standard deviation from main into a separate function. Set up the function to accept an array by its pointer (the address of the zeroth element). Test your modified program with a simple array specified when the array is initialized.

//find average, variance, and standard deviation

#include //includes standard input output

#include //includes math functions

#define n 400 //sets n equal to 400

int main()

{

//array

float a[n]= {1.8, 4.3, 15.6, 0.2, 10.7, 1.2, 0.9, 5.0, 4.6, 6.8,

4.6, 0.7, 5.2,5.5, 4.5, 5.5, 3.8, 6.8, 5.0, 1.2, 2.0, 1.1, 5.0, 3.3,

2.1, 10.9, 1.4, 1.3, 0.1, 5.0, 2.6, 1.5, 10.3, 23.9, 1.3, 1.8, 1.8,

7.1, 3.6, 9.5, 9.2, 16.1, 15.0, 0.7, 10.0, 5.9, 1.6, 2.8, 2.7, 0.8, 0.2,

6.5, 7.4, 5.2, 0.6, 2.7, 14.8, 6.8, 9.8, 14.9, 5.1, 0.9, 1.3, 4.2, 3.5,

2.2, 1.2, 6.8, 9.0, 8.9, 5.7, 11.5, 1.6, 13.2, 1.1, 3.3, 4.7, 9.9, 1.5,

9.3, 2.6, 8.5, 13.0, 8.2, 1.5, 6.0, 18.4, 1.6, 0.6, 9.1, 12.9, 7.4, 0.2,

1.1, 1.1, 1.4, 12.2, 0.3, 8.4, 11.1, 11.5, 3.2, 1.9, 0.1, 1.2, 7.6, 7.1,

3.5, 6.7, 1.5, 16.5, 1.1, 3.7, 5.7, 7.5, 13.0, 4.5, 10.9, 4.3, 3.8, 2.7,

0.6, 2.4, 7.4, 2.8, 6.2, 1.7, 3.8, 1.6, 2.4, 11.9, 6.4, 4.4, 1.3, 2.8, 0.2,

11.7, 3.9, 2.0, 5.0, 2.9, 11.9, 0.2, 0.2, 5.7, 1.3, 3.7, 1.5, 0.9, 5.6,

2.6, 5.2, 1.2, 4.6, 3.3, 1.6, 10.9, 0.3, 2.3, 1.1, 1.8, 5.5, 6.2, 6.0, 6.4,

2.0, 8.8, 1.7, 5.3, 0.2, 3.2, 13.9, 4.0, 5.8, 6.7, 0.5, 0.8, 6.8, 1.6, 1.9,

1.1, 6.3, 2.0, 0.4, 5.7, 11.2, 1.6, 1.0, 4.5, 3.5, 4.0, 2.7, 4.2, 28.5,

21.2, 4.5, 13.6, 5.5, 3.6, 1.5, 1.8, 0.6, 12.1, 2.7, 1.5, 13.5, 3.5, 2.1,

3.9, 5.3, 2.5, 4.0, 4.3, 5.4, 3.8, 2.0, 3.6, 3.8, 1.5, 4.0, 0.0, 2.9, 3.5,

0.4, 3.0, 3.8, 3.3, 0.6, 3.9, 2.1, 2.3, 3.7, 3.3, 0.1, 1.8, 9.6, 9.2, 2.0,

6.4, 6.2, 7.0, 0.7, 3.4, 5.3, 2.0, 1.2, 0.2, 9.6, 8.7, 0.3, 4.4, 4.0, 3.2,

0.5, 0.7, 4.0, 3.5, 9.2, 2.2, 10.0, 0.4, 7.2, 12.4, 18.2, 6.1, 3.5, 5.5,

5.1, 3.0, 10.9, 2.3, 2.5, 3.6, 4.4, 0.7, 3.8, 0.1, 8.6, 5.4, 2.6, 9.2, 0.6,

2.0, 9.8, 7.3, 16.1, 5.2, 6.2, 7.0, 4.7, 1.1, 8.1, 22.6, 0.9, 4.2, 6.8, 0.$

3.4, 2.8, 2.9, 9.2, 14.6, 7.6, 16.6, 2.5, 9.9, 0.2, 1.6, 2.3, 2.9, 5.2,

1.2, 1.9, 2.9, 6.8, 1.4, 6.1, 3.6, 3.6, 2.3, 12.3, 2.4, 5.3, 11.5, 14.9,

4.9, 1.6, 4.1, 4.9, 2.5, 3.9, 4.2, 8.7, 7.2, 4.6, 3.4, 1.1, 5.8, 1.8, 9.3,

3.7, 6.4, 18.1, 8.7, 4.5, 1.9, 3.1, 3.5, 0.6, 16.6, 9.5, 2.5, 7.9, 13.1,

6.7, 2.7, 1.8, 1.8, 2.6, 11.9, 8.2, 2.7, 5.2, 2.3, 8.6, 3.9, 0.9, 6.1, 3.9,

1.5, 0.7, 2.1, 0.2, 2.9, 0.9, 3.9, 6.4, 1.9, 6.1, 10.6, 11.4, 9.9, 4.3,

10.0, 5.5, 3.6, 3.0, 0.7, 2.4, 0.9, 3.3, 2.9, 9.2, 6.5, 3.8, 5.5, 3.1, 6.1,

2.9, 1.5};

//set values to floats or integers

float sum=0, avg, var, sd;

int i;

//summing and averaging of numbers

for (i=0;i

avg=sum/n;

//variance and its square root (sd)

for (i=0;i

sd=sqrt((var)/(n-1.0));

//print answers

printf("Average= %f Variance= %f S.D.= %f ", avg, var, sd);

return 0;

}

Explanation / Answer

Below is the modified C code:-

//find average, variance, and standard deviation

#include<stdio.h> //includes standard input output

#include<math.h> //includes math functions

#define n 400 //sets n equal to 400

void calculateAvgVarSd(float *a){
    //set values to floats or integers
    float sum=0, avg, var, sd;
    int i;

//summing and averaging of numbers

    for (i=0;i<n;i++){
        sum+=*(a+i);
    }

avg=sum/n;

//variance and its square root (sd)

    sum=0;
    for (i=0;i<n;i++){
        sum = sum + pow((*(a+i) - avg), 2);
    }

var=sum/(float)n;