There is a mistake while using condtional and for loop condtion.i got the value zero only. but i want values and here, A is subdiagonal, B is diagonal and C is superdiagonal.

xmax=1; ymax=20; dx=0.05; dy=0.25; dt=0.02;m=xmax/dx; n=ymax/dy; UOLD=zeros(m,n); VOLD=zeros(m,n);

for j=1:n

if i==2:m

C(i)=V(i,j)*dt/4*dy-dt/2*(dy)^2;

elseif i==1:m-1

A(i)=-V(i,j)*dt/4*dy-dt/2*(dy)^2;

elseif i==1:m

B(i)=1+U(i,j)*dt/2*dx+dt/(dy)^2;

end

end

[Torsten]

So many errors...

I suggest you first pass the 2 hours MATLAB online tutorial for free before you continue:

https://de.mathworks.com/learn/tutorials/matlab-onramp.html

[Sulaymon Eshkabilov]

Study the [while ... end] loop: https://www.mathworks.com/help/matlab/ref/while.html

Study the [for ... end] loop: https://www.mathworks.com/help/matlab/ref/for.html

Study the [if ... end] operation: https://www.mathworks.com/help/matlab/ref/if.html

Answer 1

[Atsushi Ueno]

The inside of the if sentence is never be executed even if i takes any value.

i = 3;
if i == 2:5
    disp('true');
end
i == 2:5

ans = 1×4 logical array
   0   1   0   0

if [0 1 0 0]
    disp('true');
else
    disp('false');
end

false

if [1 1 1 1]
    disp('true');
else
    disp('false');
end

true

[Atsushi Ueno]

hey, that's same with last question.

here, i couldn't get the A,B,C values while using if, elseif conditions. how to get values while using conditional state... - MATLAB Answers - MATLAB Central (mathworks.com)