Can't figure out operator use error

x = linspace(0,1,50);
y = linspace(0,1,50);
i = x(1);
j = y(1);

for i < length(x)
    for j < length(y)
        u(i,j) = (1/sinh(-pi))*sin(pi*y(j))*sinh(pi*(x(i)-1));
        j = j+1;
    end

    j = y(1);
    i = 1 + i;
end

surf(u, x, y)

File: visualization_hmw_3_q_1.m Line: 6 Column: 7
Invalid use of operator. 

[Thomas Murdoch]

I recently solved this problem and want to visualize the function 'u'. I for some reason cannot resolve the '<' error

[Star Strider]

See if the while approach will produce the desired result. I believe you are confusing it with for.

[Thomas Murdoch]

The while approach did work. I have attached my complete code here:

clear all
close all
x = linspace(0,1,50);
y = linspace(0,1,50);
i = 1;
j = 1;

while i <= length(x)
    while j <= length(y)
        u(i,j) = (1/sinh(-pi))*sin(pi*y(j))*sinh(pi*(x(i)-1));
        j = j+1;
    end

    j = 1;
    i = 1 + i;
end

surf(x, y, u)

[Walter Roberson]

Is there a particular reason to use while there instead of for ? When you are doing a fixed number of iterations, for is almost always cleaner to code.

Answer 1

[David Hill]

x = linspace(0,1,50);
y = linspace(0,1,50);
u=zeros(50);
for i =1:length(x)
    for j =1: length(y)
        u(i,j) = (1/sinh(-pi))*sin(pi*y(j))*sinh(pi*(x(i)-1));
    end
end
surf(x, y,u)

[David Hill]

Alternatively,

[x,y]=meshgrid(linspace(0,1,50));
u = (1/sinh(-pi))*sin(pi*y).*sinh(pi*(x-1));
surf(u,x,y);