Example:

Consider the following sequence of Tcl commands within XSPEC:

 XSPEC> log
 Logging to file: xspec.log
 XSPEC> set i 1 ; set product 1
 1
 XSPEC> while {$i <= 5} {
 set product [expr $product * $i]
 incr i
 }
 XSPEC> set product
 120
 XSPEC>

This would produce the following output in the file xspec.log :

 Logging to file: xspec.log
 XSPEC> set i 1 
 set product 1
 1
 XSPEC> while {$i <= 5} {;set product [expr $product * $i];incr i;}
   expr $product * $i
  set product [expr $product * $i]
  incr i
   expr $product * $i
  set product [expr $product * $i]
  incr i
   expr $product * $i
  set product [expr $product * $i]
  incr i
   expr $product * $i
  set product [expr $product * $i]
  incr i
   expr $product * $i
  set product [expr $product * $i]
  incr i
 XSPEC> set product
 120
 XSPEC>