Conversion to cell from double is not possible.

clc
close all

n = input("enter the basis matrix dimension:  ");
alpha2 = ones(1,n)*sqrt(2/n);
alpha2(1) = sqrt(1/n);
alpha1 = ones(1,n)*sqrt(2/n);
alpha(1) = sqrt(1/n);
for u = 0:n-1
    for v = 0:n-1
        for x = 0:n-1
            for y = 0:n-1
                a {u+1,v+1}(x+1,y+1) = alpha1(u+1)*alpha2(v+1)*...
                    cos((2*x+1)*pi*u/(2*n))*cos((2*y+1)*pi*v/(2*n));
            end
        end
    end
end
mag = a;
figure();
k=1;

for i = 1:n
    for j = 1:n
        subplot(n,n,k)
        imshow(mag{i,j})
        k = k+1;
    end
end
Conversion to cell from double is not possible.

Error in dctma (line 13)
                a {u+1,v+1}(x+1,y+1) = alpha1(u+1)*alpha2(v+1)*...
 

[Jonas]

i dont have problems running this code. what was your input as n?

[Divya]

i am enterring 2 or 4, but error is same.

Answer 1

[Jan]

If a variable is not defined before, the default type is double . You want to access a as a cell, so define it accordingly:

a = cell(n, n);   % Preallocate as a cell
for u = 0:n-1
    for v = 0:n-1
        for x = 0:n-1
            for y = 0:n-1
                a {u+1,v+1}(x+1,y+1) = alpha1(u+1)*alpha2(v+1)*...
                    cos((2*x+1)*pi*u/(2*n))*cos((2*y+1)*pi*v/(2*n));
            end
        end
    end
end

[Divya]

Thanku so much, now it is working fine.