Created attachment 67201 [details]
plot file

Version:           unspecified
OS:                Linux

Let's define
g(x)= sin(pi*x)/(pi*x)
h(x,k)=g(x-k)
i(x,k)=g(x+k)

I cannot define the following function:
j(x,k)=h(x,k)+i(x,k)

Says: "The function does not have the correct number of arguments"

Reproducible: Always



Expected Results:  
I expected kmplot to understand and compute a cartesian function with a parameter, defined from another cartesian function with the same parameter.
j(x,k)=h(x,k)+i(x,k)