Matvec Users’ Guide

4.3. WHILE STATEMENT 37
that all those three sections can be omitted simultaneously, thus for (; ;) BLOCK construction provides
user an infinite loop. The break statement is the only wat to exit such an infinite loop.
The second form of for statement is similar to that in Maple language. The expression must evaluate to
a either matrix, or vector, or list, otherwise a run-time error will result. The for statement simply executes
the BLOCK the N times where N is the size of expression unless it encounters the break statement, which
will terminate the nearest for–loop execution. The for statement can be nested, too. For instance,
> A = zeros(3,4);
> for (i=0; i A
Col 1 Col 2 Col 3 Col 4
Row 1 2.00000 3.00000 4.00000 5.00000
Row 2 3.00000 4.00000 5.00000 6.00000
Row 3 4.00000 5.00000 6.00000 7.00000
4.3 While Statement
The while statement is very similar to that in C/C++.
while (expression) BLOCK
If the expression evaluates to anything rather than zero, then the BLOCK is executed, otherwise goes to
the statement right after the BLOCK.
For example,
> i=1; j=0;
> while(i > 10) {
j += i++;
}
> j
45
4.4 Repeat–Until Statement
The repeat statement is very similar to that in PASCAL language.
repeat BLOCK until (expression)
the BLOCK is executed until the expression evaluates to anything rather than zero. Then, it goes to the
statement right after the expression.
For example,
> i=1; j=0;
> repeat {
j += i++;
} until (i >= 10)
> j
45