Really could use a sign transfer function

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Permalink Reply by biboarchitect on June 21, 2012 at 11:53pm

Sin(x) you mean?

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Permalink Reply by Danny Boyes on June 22, 2012 at 2:40am

I think it refers to the SIGN transfer function of Fortran days.

Where you could specify two variables Sign(x,y) which would change the sign of x if y was different.

eg

sign(1,2) = 1

sign(1,-2) = -1

sign(-1,2) = 1

sign(-1,-2) = -1

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Permalink Reply by Danny Boyes on June 22, 2012 at 3:13am

Very odd it didn't seem to display the text.

Here's a VB  Script of it. Probably a more elegant way to achieve this but it would do for now 

Attachments:

• sign.gh, 2 KB

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Permalink Reply by Randolph Fritz on June 22, 2012 at 11:24am

Thanks.

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Permalink Reply by Randolph Fritz on June 22, 2012 at 11:28am

I was thinking more of the more modern sign() function, where:

                   -1 if x < 0

sign(x) =        0 if x = 0

                    1 if x > 0

This can be used as a sign transfer function by multiplication:

  sign(x) * whatever

I ended up writing something like "if(x>0,1,-1)", which worked, but isn't very elegant.

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Permalink Reply by Randolph Fritz on July 9, 2012 at 12:43pm

A very late note in this thread; this is called the "signum" function, usually denoted "sgn," though some computer languages make it "sign." See http://mathworld.wolfram.com/Sign.html.  I still wish Grasshopper included it.

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Permalink Reply by Igor on July 9, 2012 at 2:51pm

Try to use  if(x<0,-1,0)+if(x>0,1,0) , why would be not ....

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Permalink Reply by Igor on July 9, 2012 at 3:11pm

...or if(x=0,0,x/abs(x)) ......

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