if

Scilab Function
Last update : 25/04/2007

if - conditional execution

### Calling Sequence

  `if expr1 then statements`
  `elseif expri then statements`
  `....`
  `else statements`
  `end`

### Description

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.

### Examples

       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

### See Also

`try` , `while` , `select` , `boolean` , `end` , `then` , `else` ,