How do I set every other number in an array to a specific number with one line?

I'm trying to set every other element within an 5x5 array to 100 (so (1,1) (1,3) (1,5) ETC.) Within a single line of code. Im not sure how to do this, please help!

Answer 1

[Stephen23]

>> M = zeros(5);
>> M(1:2:end) = 100
M =
   100     0   100     0   100
     0   100     0   100     0
   100     0   100     0   100
     0   100     0   100     0
   100     0   100     0   100

[Asrorkhuja Ortikov]

that works only with odd number sized matrix

Answer 2

[Jan]

See Stephen's answer, if you need the checkerboard distribution for an odd number of elements only. If the matrix can have even or odd number of rows and columns:

n = 5;
v = rem(1:n, 2);
M = (v.' == v) * 100;  % Auto-expand, needs Matlab >= R2016b

With older Matlab versions:

M = bsxfun(@eq, v.', v) * 100;

EDITED: Less multiplications and therefore slightly faster:

n = 5;
v = rem(1:n, 2);
M = v.' .* (v * 100);  % Auto-expand, needs Matlab >= R2016b