# Comments:Complex Numbers

From GeoGebra Manual

## Workaround: IsComplex[]

Sometimes you may want to check if a number is treated as complex number in GeoGebra, as function such as `x()`

and `y()`

do not work with real numbers. As there is no such command as `IsComplex`

you currently have to employ a small trick to check if the number `a`

is complex: `complex = IsDefined[sqrt(a) + sqrt(-a)] ∧ (a ≠ 0)`

.

**Note:**Complex with imaginary part 0, like

`a = 2 + 0i`

, also pass this test. If you just want to check if the imaginary part of a complex number `a`

is not 0 you can use `y(a) != 0`

.