Interconnected Parameters a=b and b=a

[Thomas Nymann]

Hi gdl wizards.

Can anybody help create (Parameter) script that will adjust the values in a way that if parameter "xx" changes then parameter "f1" will change accordingly - and then if paramter "f1" changes parameter "xx" will update accordingly.

I know how to do this:

f1=ATN(xx)
PARAMETERS f1=f1

xx=TAN(f1)
PARAMETERS xx=xx

But in this case "f1" becomes locked!

I need both parameters to be able to control the other one, at any given time!

Hope the information is sufficient enough ‌‌

Cheers

Thomas

[neilmcallister]

If you look at the section titled "Connections between parameters" on this page it should explain how to do it.

https://gdl.graphisoft.com/gdl-basics/parameter-logic

I've not tried it myself, but it looks as though you check the value of GLOB_MODPAR_NAME to see which parameter is being changed and act accordingly.  This prevents it getting into a circular loop.

[Lingwisyer]

IF GLOB_MODPAR_NAME = "A" then
B = xA
PARAMETERS B = B
endIF

IF GLOB_MODPAR_NAME = "B" then
A = B/x
PARAMETERS A = A
endIF

[Barry Kelly · Accepted solution]

Yes GLOB_MODPAR_NAME is your friend here.

I would not use ...

if GLOB_MODPAR_NAME = "xx" then
	f1 = xx * 2
	parameters f1 = f1
else
	xx = f1 / 2
	parameters xx = xx
endif

That will work but means if 'xx' is modified,' f1' will update, but if any other parameter is changed 'xx' will be updated.

If you don't want that and only want 'xx' to update when 'f1' is changed then just use separate routines ...

if GLOB_MODPAR_NAME = "xx" then
	f1 = xx * 2
	parameters f1 = f1
endif

if GLOB_MODPAR_NAME = "f1" then
	xx = f1 / 2
	parameters xx = xx
endif

Barry.

[Thomas Nymann]

Thanks Barry.

That did the trick. Much appreciated 🙂

[Thomas Nymann]

Thanks for that fast reply Lingwisyer. 🙂