how to switch from C language to matlab?
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i should rewrite this code in C on matlab
#include<stdio.h>
int main()
{
int i,j,k,n;
float A[20][20],c,x[10],sum=0.0;
printf("\nEnter the order of matrix: ");
scanf("%d",&n);
printf("\nEnter the elements of augmented matrix row-wise:\n\n");
for(i=1; i<=n; i++)
{
for(j=1; j<=(n+1); j++)
{
printf("A[%d][%d] : ", i,j);
scanf("%f",&A[i][j]);
}
}
for(j=1; j<=n; j++) /* loop for the generation of upper triangular matrix*/
{
for(i=1; i<=n; i++)
{
if(i>j)
{
c=A[i][j]/A[j][j];
for(k=1; k<=n+1; k++)
{
A[i][k]=A[i][k]-c*A[j][k];
}
}
}
}
x[n]=A[n][n+1]/A[n][n];
/* this loop is for backward substitution*/
for(i=n-1; i>=1; i--)
{
sum=0;
for(j=i+1; j<=n; j++)
{
sum=sum+A[i][j]*x[j];
}
x[i]=(A[i][n+1]-sum)/A[i][i];
}
printf("\nThe solution is: \n");
for(i=1; i<=n; i++)
{
printf("\nx%d=%f\t",i,x[i]); /* x1, x2, x3 are the required solutions*/
}
return(0);
}
1 个评论
Geoff Hayes
2022-5-17
@AURORA SCALINCI - what have you tried so far? Please see scripts vs functions, matrices and arrays and for to get an idea of where to start.
回答(1 个)
Pratik Pawar
2022-5-20
This code is performing Gaussian Elimination.
Please refer to the C code converted to MATLAB below:
% script_name.m
% input augmented matrix
n = input('Enter the order of matrix: ');
disp(' ');
A = zeros(n, n+1);
for i=1:n
for j=1:n+1
A(i,j)=input(sprintf('Input the matrix value for (%d,%d): ', i, j));
end
end
% separate last column of augmented matrix as b and define x
b = A(1:n, n+1);
% forward elimination code to convert matrix A to upper triangular matrix
for j = 1:n-1
for i = n:-1:j+1
m = A(i,j)/A(j,j);
A(i,:) = A(i,:) - m*A(j,:);
b(i) = b(i) - m*b(j);
end
end
% back substitution to find x
x = zeros(n,1);
x(n) = b(n)/A(n,n);
for i = n-1:-1:1
sum = 0;
for j = n:-1:i+1
sum = sum + A(i,j)*x(j);
end
x(i) = (b(i)- sum)/A(i,i);
end
% display roots
x
MATLAB allows processing all the values in a matrix using single arithmatic operator. So, a doble 'for loop' can be avoided to improve time complexity.
% preferred
% script_name.m
% input augmented matrix
n = input('Enter the order of matrix: ');
disp(' ');
A = zeros(n, n+1);
for i=1:n
for j=1:n+1
A(i,j)=input(sprintf('Input the matrix value for (%d,%d): ', i, j));
end
end
% separate last column of augmented matrix as b and define x
b = A(1:n, n+1);
x = zeros(n, 1);
% forward elimination code to convert matrix A to upper triangular matrix
for i=1:n-1
m = A(i+1:n, i) / A(i, i);
A(i+1:n, :) = A(i+1:n, :) - m*A(i, :);
b(i+1:n, :) = b(i+1:n, :) - m*b(i, :);
end
% back substitution to find x
x(n, :) = b(n, :) / A(n, n);
for i=n-1:-1:1
x(i, :) = (b(i, :) - A(i, i+1:n)*x(i+1:n, :))/A(i, i);
end
% display roots
x
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