CODE 10

//GAURAV MITTAL(2K9/EE/830)

//QUESTION 10. To find out the unknowns (x,y,z) using Gauss elimination method

#include"stdio.h"

#include"conio.h"

int main()

{

int i,j;

float a[3][4],b[3][4],c[4][4];

float x,y,z,p,q,r;

m:

printf("\nEnter the coefficients: ");

printf("\n\n");

for(i=0;i<3;i++)

{

printf("\n");

printf("Enter a1 : ");

scanf("%f",&a[i][0]);

printf("Enter b1 : ");

scanf("%f",&a[i][1]);

printf("Enter c1 : ");

scanf("%f",&a[i][2]);

}

printf("\n\nEnter the constants: ");

printf("\n\n");

printf("Enter d1 : ");

scanf("%f",&a[0][3]);

printf("Enter d2 : ");

scanf("%f",&a[1][3]);

printf("Enter d3 : ");

scanf("%f",&a[0][3]);

if(a[0][0]!=0.0)

{

p=a[1][0];

q=a[0][0];

r=a[2][0];

for(j=0;j<=3;j++)

{

b[0][j]=-(p/q)*a[0][j];

a[1][j]+=b[0][j];

c[0][j]=-(r/q)*a[0][j];

a[2][j]+=c[0][j];

}

p=a[2][1];

q=a[1][1];

for(j=0;j<=3;j++)

{

b[1][j]=-(p/q)*a[1][j];

a[2][j]+=b[1][j];

}

printf("\n\nThe matrix becomes\n");

for(i=0;i<3;i++)

{

for(j=0;j<4;j++)

{

printf("%.4f\t",a[i][j]);

}

printf("\n");

}

z=a[2][3]/a[2][2];

y=(a[1][3]-a[1][2]*z)/a[1][1];

x=(a[0][3]-a[0][2]*z-a[0][1]*y)/a[0][0];

printf("\n\n\nThe solution is\n");

printf("\nX=%f,\tY=%f,\tZ=%f",x,y,z);

}

else

{

printf("\nThe first cofficient must not be zero,Enter again");

goto m;

}

getch();

return 0;

}