Crank-Nicolsan scheme to solve heat equation in fortran programming

Crank-Nicolsan scheme to solve heat equation in fortran programming

I am trying to solve the 1d heat equation using crank-nicolson scheme. And for that i have used the thomas algorithm in the subroutine. Can you please check my subroutine too, did i missed some codes?? Im trying to connect the subroutine into main program and link it together to generate the value of u(n+1,j) and open the output and graphics into the matlab files.

There were no complier errors. So after i complie and run the program, i got run-time error.
Run-time Error:
Error 112, Reference to undefined variable,array element or function result[/UNDEF]

CRANK_NICOLSON ~THOMAS_ALGORITHM- in file crank_nicolsonf.95 at line : q = a(j)/b(j-1)

main - in file crank_nicolson.f95 at line : call thomas_algorithm(a,b,c,d,JI+1,u_new)


Downloadtext/plain fortrancode.txt2.12 KB
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The code posted compiles/runs correctly using the Intel Fortran compiler for Windows and Linux.

The code posted does not match the error. I guess the error originates from matlab which I do not have so I could not produce the error. The code posted calls the thomas_algorithm() routine with the argument “JI” but the error shows when it was compiled/run and the error occurred that the call was made with the argument “JI+1”. The latter argument (JI+1) references beyond the end of the arrays in the “do j=2,JI” inside the thomas_algorithm() routine. It appears that may be what was detected.

I have some tips for you! I recomend that you initialize all your variables in order to avoid problems. I recomend that you initialize your arrays with 1 not zero.

I notice that you posted this at least twice, probably to different forums.

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