if then else - conditional execution
The if statement evaluates a logical expression and executes a group of statements when the expression is true.
The expri are expressions with numeric or boolean values. If expri are matrix valued the condition is true only if all matrix entries are true or different from zero.
The optional elseif and else provide for the execution of alternate groups of statements. An end keyword, which matches the if, terminates the last group of statements. The line structure given above is not significant, the only constraint is that each then keyword must be on the same line as its corresponding if or elseif keyword.
The keyword then can be replaced by a carriage return or a comma.
Warning: the number of characters used to define the body of any conditionnal instruction (if while for or select/case) must be limited to 16k.
i=2
for j = 1:3,
if i == j then
a(i,j) = 2;
elseif abs(i-j) == 1 then
a(i,j) = -1;
else a(i,j) = 0;
end,
end