[alexis1129]

I have this Fortran code and needed to convert it to C, I have no knowledge in Fortran, so can anyone help me

	
Fortran
program main 
c	main program to illustrate eigenproblem solvers 
c	ndim array dimension, ndim = 6 in this example 
c	n number of equations, n 
c	a coefficient matrix, A(i,j) 
c 	x eigenvector, x(i) 
c	y intermediate vector, y(i) 
c	norm specifies unity component of eigenvecor 
c	iter number of iterations allowed 
c	tol convergence tolerance 
c	shift amount by which eigenvalue is shifted 
c	iw intermediate results output flag: 0 no, 1 yes 
	dimension a(6,6) ,x(6) ,y(6) 
	data ndim = 6, n = 3,norm =3 , iter = 50, tol = 1.e-6, shift = 0.0, iw=1 / 6, 3, 3, 50,1.e-6,0.0,1/ 
c	data ndim, n,norm, iter, tol, shift, iw/6, 3, 3, 50, 1.e-6, 13.870584, 2/ 
	data (a(i,1),i=l,3) / 8.0, -2.0, -2.0 / 
	data (a(i,2),i=i,3) /-2.0, 4.0, -2.0 / 
	data (a(i,3),i=i,3) /-2.0, -2.0, 13.0 /
	data (x(i),i=l,3) / 1.0, 1.0, 1.0 /  
	write (6,1000) 
	do i=1, n 
	  write (6,1010) i, (a(i,j),j=l,n),x(i) 	
	end do 
	if (shift.gt.0.0) then 
	  write (6,1005) shift 
	  do i=i,n 
	    a(i, i)=a(i,i) -shift 
	    write (6,1010) i, (a(i,j),j=i,n) 
	  end do 
	end if 
	call power ( ndim, n, a, x, y, norm, i ter , t ol , shift, i w , k, ev2 ) 
	write (6,1020) 
	write (6,1010) k, ev2, (x(i),i=l,n) 
	stop 
1000	format (' The power method'/' '/' A and x(O) '/' ') 
1005	format (' '/' A shifted by shift = ',flO. 6/' ') 
1010	format (ix, i$, 6f12.6) 
1020	format (' '/' k lambda and eigenvector components'/' ') 
	end 
	subroutine power (ndim, n, a, x, y, norm, i ter, tol , shift, iw, k, ev2 ) 
c	the direct power method  
	dimensiOn a(ndim, ndim),x(ndim),y(ndim) 
	evl = 0.0 
	if (iw. eq.1) write (6,1000) 
	if (iw. eq.1) write (6,1010) k, evl, (x(i),i=l,n) 
	do k=1,iter 
c 	calculate y(i) 
	do i=l,n 
	 y(i) =0.0 
	  do j=l,n 
	   y(i) =y(i) +a (i, j) *x(j) 
	  end do 
	end do 
c 	calculate lambda and x(i) 
	ev2 =y(norm) 
	if (abs (ev2) .le.1. Oe-3) then 
	write (6,1020) ev2 
	return 
	else 
	do i=l,n 
	x (i) =y(i )/ev2 
	end do 
	end if 
	if (iw. eq. 1) write (6,1010) k, ev2, (x(i),i=i,n) 
c 	check for convergence 
	if (abs(ev2-evl) .Ie. tol) then 
	if (shift.ne.O.O) then 
	evl =ev2 
	ev2=ev2+shi ft 
	write (6, 1040) evl, ev2 
	end if 
	return 
	else 
	evl =ev2
	end if 
	end do 
	write (6, 1030) 
	return 
1000 	format (' '/' k lambda and eigenvector components'/' ') 
I010 	format (ix, i3,6f12.6) 
1020 	forma (' '/' lambda = ',elO.2, ' approaching zero, stop') 
1030 	format (' '/' Iterations did not converge, stop'] 
1040 	format (' '/' lambda shifted =',f12.6,' and lambda =',fi2.6) 
end 

 
C PROGRAM
#include <stdio.h>
#include <conio.h>
#include <math.h>

int main()
{
    double A[3][3] = {8,-2,-2,-2,4,-2,-2,-2,13};
    double X[6], Y[6];    
    int x,y,ndim = 6,n = 3,norm = 3, iter = 50, tol = 1, iw=1;
    double shift = 0.0,tol = 1e-6; 
    
    for (x=0;x<=2;x++)
    {
        for (y=0;y<=2;y++)
        {
            printf("%7.4f\t",A[x][y]);
        }
        printf("\n");
    }  
    getch();
}

[ishkabible]

do you know what the fortan code does? if so don't worry about coping it just write the C code for what it does.

[no2pencil]

alexis1129, on 26 May 2012 - 08:36 AM, said:

I have no knowledge in Fortran

So basically you found code to fit a project or assignment, & want us to convert it. Thus you still put no effort into it, & walk away with the project completed.

I'm closing this topic, feel free to private message me with any questions.

** Topic Closed **