I am a beginner in using Tcl. I am using it as VMD (molecular visualization) software uses it as a scripting language.
I have a list of co-ordinates of atom positions for a protein like: {{1 2 3} {7 9 13}, ...} I have a separate list of the same length with different positions say: {{3 5 2} {7 3 8}, ...}.
VMD has an inbuilt vecsub function which can subtract {1 2 3} and {3 5 2} to give {-2 -3 1}. I have written a foreach loop to iterate on the entire list and calculate vecsub.
My code is as follows:\
set sel1 [atomselect 0 "protein"] # selecting protein1set sel2 [atomselect 1 "protein"] # selecting protein2# create a list of same length as protein to store values# $sel1 get index returns length of proteinforeach i [$sel1 get index] { lappend x 0 }# veclength2 returns square of vector length# $sel1 get {x y z} returns a position list as described earlierforeach i [$sel1 get index] { lset x $i [expr [veclength2 [vecsub [lindex [$sel1 get {x y z}] $i] [lindex [$sel2 get {x y z}] $i]]]]}Is there another way to do this in Tcl? Similar to python array subtraction perhaps?
