Sine wave

Hello Everyone,

With these codes, the matrix A have 4000 points and this take a long time, how can I let this program work quickly with less Matrix and the same wavelength 100 um?

Thanks

xRes = 1; % Sets the resolution (step length), in µm, along the x-axis.
yRes = 1; % Sets the resolution (step length), in µm, along the y-axis.
zRes = 1; % Sets the resolution (step length), in µm, along the z-axis.

xLength = 4000; % Sets the length of the surface in X.
yLength = 3000; % Sets the length of the surface in Y.

wavelength = 100;

f = @(x) 3*sin(x*2*pi/wavelength) + 1003; % The function for the sine wave with the 
% amplitude 3 µm and wave length of about 100 µm. Mean level is 
% 1003 µm. 

% Prints the sine wave into a matrix:
A = zeros(yLength/yRes+1,xLength/xRes+1);
for k = 1:length(A(:,1))
    for l = 1:length(A(1,:))
        A(k,l) = f(l-1);
    end
end

Answer 1

[Walter Roberson]

All of your rows are the same, so consider using repmat()

[simira atraqi]

I am sorry but I didn't get it. What you mean?

[Walter Roberson]

for k = 1:length(A(:,1))
    for l = 1:length(A(1,:))
        A(k,l) = f(l-1);
    end
end

You are not changing f within the loops, so A(1,5) = f(4) and A(2,5) = f(4) and A(3,5) = f(4) and so on -- each A(k,l) is exactly the same as A(k-1,l) . Therefore you only need to build A(1,:) and then you copy the row as many times as needed.

for l = 1 : size(A,2)
    A(1,l) = f(l-1);
end
A = repmat(A(1,:), size(A,1), 1);  %replicate the row