for VARIABLENAME = FIRST_VALUE : INCREMENT : LAST_VALUE
something
end
is nearly equivalent to
VARIABLENAME = FIRST_VALUE;
while VARIABLE_NAME <= LAST_VALUE
something
VARIABLE_NAME = VARIABLE_NAME + INCREMENT;
end
(The differences between the two have to do with the value that VARIABLENAME is left at if FIRST_VALUE > LAST_VALUE when INCREMENT is positive, or FIRST_VALUE < LAST_VALUE when INCREMENT Is negative; and also have to do with the value that VARIABLENAME will be left with after the last iteration in two different situations.)
