[ESPResSo] Re: Doubt in an analysis TCL script provided with Espresso

[Axel Arnold]

Am Montag 21 Januar 2008 12:38 schrieb prateeksha s:
> Hi,
>
> I am developing using Espresso code, and I'm converting the
> fluctuations.tclscript, found in packages/mbtools/analysis/, to C. I
> encountered this piece
> of TCL which I do not understand, hence, I'm unable to translate it to C.
>
> The difficult-to-understand code is in italics :
> set re [expr *[lindex [lindex $rawmodes 1 $i $j] 0]**$norm]
> set im [expr *[lindex [lindex $rawmodes 1 $i $j] 1]**$norm]
>
> *rawmodes* is a 2D array( or is it? ) so trying* rawmodes[1][i][j][0]* just
> doesn't make sense.
> Can somebody please clarify.

rawmodes is not a simply array, but has the form "{Modes} {2d-array of complex 
values}", where each complex number is itself a two-element array, therefore 
the second element is 3d. Therefore, [lindex [lindex $rawmodes 1 $i $j] 0] is 
the real part of mode i,j, and  [lindex [lindex $rawmodes 1 $i $j] 1] the 
imaginary part. So, the first 1 after rawmodes selects the 2d-array instead 
of the "Modes" string, and the last 0/1 the real/imaginary part.

Axel

-- 
Dr. Axel Arnold 
Fraunhofer Institute for Algorithms and Scientific Computing (SCAI)
Schloss Birlinghoven
53754 Sankt Augustin
Germany