kindly help in the conversion of fortran code to matlab

[Walter Roberson]

Is th a function or an array declared with indices that start from 0 ?

[Walter Roberson]

do j=0,m

would be written in MATLAB as

for j=0:m

end do would be written in MATLAB as

end

float(n) would be written in MATLAB as double(n), but it is more likely that you would just make m double precision in which case you could skip doing the float() step.

write(5,*)P,Q,R

would be written in MATLAB as

fprintf('%g %g %g\n', P, Q, R)

[Oluwaseyi Aliu]

I still dont understand sir. Can you comment on the entire code pls? is mode of initialisation in fortran the same with Matlab? I am actually working on a 100x100 matices

[Walter Roberson]

snul = 0.0;
snur = 0.0;
for j = 0:m
    rnul = (th(0,j) - th(1,j)) * n;
    rnur = (th(n-1,j) - th(n,j)) * n;
    snul = snul + rnul;
    snur = snur + rnur;
    fprintf('%g %g %g\n' j/m, rnul, rnur);
end
avnl = snul / m;
avnr = snur / m;
fprintf('%g %g %g\n', ra, avnl, avnr);

I do not see any 100 x 100 matrices, not unless you are saying that th is a matrix. In fortran it is possible but not all that common to declare arrays to start from index 0, or any other index. I would want to see the statements that defined th, such as

REAL*8 th(100,100)

but it could not be exactly like that if th is a matrix being indexed at 0.

[Oluwaseyi Aliu]

sir, here is the initialisation;

Answer 1

[Walter Roberson]

n = 100; m = 100;
c8 = length(0:8);
f = zeros(c8, n+1, m+1);
feq = zeros(c8, n+1, m+1);
rho = zeros(c8, n+1, m+1);
w = zeros(1, c8);
cx = zeros(1, c8);
cy = zeros(1, c8);
u = zeros(n+1, m+1);
v = zeros(n+1, m+1);
g = zeros(c8, n+1, m+1);
geq = zeros(c8, n+1, m+1);
th = zeros(n+1, m+1);
i = 0;

%then some code to read the data. 

%then
snul = 0.0;
snur = 0.0;

for j = 0:m
    rnul = (th(1+0,1+j) - th(1+1,1+j)) * n;
    rnur = (th(1+n-1,1+j) - th(1+n,1+j)) * n;
    snul = snul + rnul;
    snur = snur + rnur;
    fprintf('%g %g %g\n' j/m, rnul, rnur);
end
avnl = snul / m;
avnr = snur / m;
fprintf('%g %g %g\n', ra, avnl, avnr);

[Oluwaseyi Aliu]

many thanks!