There is no "ind" function in that code.
What the code is doing is adding values to the end of a list.
If Blt(1) is 1, then add 1 to the end of the list.
Then if Blr(1) is 1, add 2 to the end of the list (that might have been updated in the previous step.)
Then if Blt(2) is 1, add 2*NE1+1 to the end of the list.
And so on.
The [] is the same as horzcat() for this purpose, so you could write it as
if Blt(1) == 1
indBl = horzcat(indBl, 1);
end
You could also write it as
if Blt(1) == 1
indBl(end+1) = 1;
end
