Reading one or two arguments

[HillyBoy]

Hi,

This is my first post on this forum. I have been using a HP-48GX for some 30 years now, but that died on me a few days ago. I replaced it with a HP-Prime and try to understand the current PPL language.

On my 48GX I had a small program that allowed me to convert a vector to its two arguments and vice versa. These vectors I use a lot in land-surveying: by switching from and to polar mode I can easily convert a coordinate-pair to distance and argument and vice versa (and add sets to each other). On the Prime I can do the same using a complex in the following notation: (a,b).

Starting point is one or two arguments on the stack.
The problem I now have is that after testing the first argument on the stack I need to make a decision:
IF TYPE(Arg1) == 0... I need to read to read Arg2 and return them as complex (Arg1, Arg2)
IF TYPE(Arg1) == 3... there is only one complex argument available, all I need to do is return its length and argument to the stack.

Reading two arguments is easy, provided they are available:
EXPORT MyProg(Arg1, Arg2)

But as I do not know in advance whether I can get 1 or 2 arguments, I need to start my program as

EXPORT MyProg(Arg1)

and test Arg1 first, before reading Arg2 when TYPE(Arg1)==0.

The other problem I have is how to return two arguments to the stack...

thanks in advance for your suggestions,
Nicolàs