# isinf

isinf(f) -> Bool

Test whether a number is infinite

## Examples

1. Check if a number is infinite:

``````julia> isinf(5.0)
false``````

This example checks if the number `5.0` is infinite. Since `5.0` is not infinite, it returns `false`.

2. Determine if a negative number is infinite:

``````julia> isinf(-Inf)
true``````

Here, the function `isinf` is used to check if the negative infinity value `-Inf` is considered infinite. It returns `true` as `-Inf` is indeed infinite.

3. Check if a positive value is infinite:

``````julia> isinf(1.0 / 0.0)
true``````

In this example, the expression `1.0 / 0.0` is evaluated, which results in a positive infinity value. The `isinf` function correctly identifies it as infinite and returns `true`.

Common mistake example:

``````julia> isinf("hello")
ERROR: MethodError: no method matching isinf(::String)``````

In this example, the `isinf` function is applied to a string `"hello"`. However, `isinf` is meant to check for infinity in numbers, not strings. Ensure that the argument provided to `isinf` is a valid numeric value to avoid such errors.