How to read data from a matrix according to the lower and upper index range

Given one logical matrix a, b defines the lower and upper index range of each row of a to be 1. May I know how to vectorize the following code, as the loop is huge (1,000,000 loops) for the real case?

a=zeros(5,24,'logical');
b=[2 4;5 7;8 9;1 10;12 15];
for i=1:5
    a(i,b(i,1):b(i,2))=1;
end

Answer 1

[sloppydisk]

Define a grid to perform logical indexing on:

n = 24;
m = 5;
gridx =  repmat(1:n, m, 1);
b=[2 4;5 7;8 9;1 10;12 15];
a = gridx >= b(:, 1) & gridx <= b(:, 2);

That should do the trick.

[Chaoyang Jiang]

Thanks a lot for your answer!