Also remember "column 7" to start (probably because of the keypunch origins). We occasionally have to do some minor tweaks to the FORTRAN code, and I'm always surprised to see that old friend, my first programming language.... Here are some of the rules for the columns for FORTRAN 77 (I'm not sure if we're using that or F90).

Col. 1 : Blank, or a "c" or "*" for comments
Col. 1-5 : Statement label (optional)
Col. 6 : Continuation of previous line (optional)
Col. 7-72 : Statements
Col. 73-80: Sequence number (optional, rarely used today)

I had a similar question as the OP via email recently about the "log" operator.

ccalc 'exp(1)'
2.718282

ccalc 'log(2.718)'
0.999896

ccalc 'log10(10)'
1.000000

ccalc 'log(10)'
2.302585

I think it's obvious from these examples "log" is a natural log, and "log10" is the base 10 log.

In a related vein, the sin,cos,tan operators all use radians while the sind,cosd,tand use degrees. The inverse trigonometric functions all return radians. (I hadn't realized that behavior regarding negative numbers before either.)

AFNI doesn't deal with NaN's and similar codes. We often see these in output from SPM and other matlab processing; consequently we incorporate the float_scan equivalent function in the GUI. See AFNI_FLOATSCAN environment variable in README.environment and the float_scan program.