# Revision history [back]

### Multivariate piecewise function?

Hi,

How can I define a function like this? f(x,y) = x*y

when (x > 0),(y>0),

f(x,y) = -x*y

when (x <= 0), (y <=0)

### Multivariate piecewise function?

Hi,

How can I define a function like this? this?

f(x,y) = x*y

, when (x > 0),(y>0),0),(y>0)

f(x,y) = -x*y

, when (x <= 0), (y <=0)