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# +Expr1 =< +Expr2

Succeed if the value of Expr1 is less than or equal to the value of Expr2.
*Expr1*
- An arithmetic expression
*Expr2*
- An arithmetic expression

## Description

Both arguments are evaluated and their types adjusted. Then the
resulting numbers are compared. The predicate succeeds if the value of
Expr1 is less than or equal to the value of Expr2. If the system is in
coroutining mode and the arguments are not ground, this predicate delays
until the expressions are fully instantiated.
The predicate also delays when the comparison involves bounded reals,
and the compared values overlap such that the result is undecidable.

### Modes and Determinism

### Modules

This predicate is sensitive to its module context (tool predicate, see @/2).
### Fail Conditions

fails if the value of Expr1 is greater than the value of Expr2
### Exceptions

*(4) instantiation fault *
- Expr1 or Expr2 is a variable (non-coroutining mode only).
*(5) type error *
- Expr1 or Expr2 is not an arithmetic expression.

## Examples

Success:
5 - 3 =< 6 / 2.
1 =< sin(pi/2). % 1 converted to 1.0
Fail:
2 + 5 =< 2 * 3.
Error:
_ =< 10. (Error 4)
"s" =< 10. (Error 5)

## See Also

iso_light : =< / 2, suspend : =< / 2, iso_strict : =< / 2, ic : =< / 2, eplex : =< / 2, is / 2, =:= / 2, =\= / 2, >= / 2, < / 2, > / 2