AFNI Message Board

Dear AFNI users-

We are very pleased to announce that the new AFNI Message Board framework is up! Please join us at:

https://discuss.afni.nimh.nih.gov

Existing user accounts have been migrated, so returning users can login by requesting a password reset. New users can create accounts, as well, through a standard account creation process. Please note that these setup emails might initially go to spam folders (esp. for NIH users!), so please check those locations in the beginning.

The current Message Board discussion threads have been migrated to the new framework. The current Message Board will remain visible, but read-only, for a little while.

Sincerely, AFNI HQ

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Bob Cox
December 11, 2016 12:21PM
You can use the ccalc program to try out AFNI expressions. As in 
calc> sqrt(-1)
Z = 1
calc> log(-3)
Z = 1.09861
calc> log(3)
Z = 1.09861
calc> log(0)
Z = 0
Showing that I was wrong in my previous post: sqrt(x) is really sqrt(abs(x)) (similarly for log()). Note log(0)=0, an indication of avoiding blowups.

The calc programs are based on some functions I wrote in the mid 1980s for parsing and evaluating arithmetic expressions. I believe in 1983-4, so they are around 33 years old now (the functions, not the programs). They still work, even though written in Fortran, so I've never really updated them except around the edges.
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Subject Author Posted

3dcalc

CD-Dan December 10, 2016 10:03PM

Re: 3dcalc

ptaylor December 11, 2016 03:29AM

Re: 3dcalc

Bob Cox December 11, 2016 07:31AM

Re: 3dcalc

ptaylor December 11, 2016 09:48AM

Re: 3dcalc

Bob Cox December 11, 2016 12:21PM

Re: 3dcalc

ptaylor December 11, 2016 12:53PM

Re: 3dcalc

Bob Cox December 11, 2016 06:42PM

Re: 3dcalc

Daniel Glen December 12, 2016 01:10PM