As a result of a discussion in the chatroom today (July 9, 2002,)
concerning the heat wave here(Kansas City, Missouri), I was
asked to use a 'saner' temperature scale than Fahrenheit...
so ...

----
 #convert degrees F to degrees C
 proc f2c { f } {
  	set res [expr int (($f - 32) * (5/9.))]	
 }

 #convert degrees C to degrees F
 proc c2f { c } {
	set res [expr  int (($c * (9/5.)) + 32) ]
 }

 #create GUI -not elegant scripting, but it works
 label .fl -text "Degrees F:"
 entry .ef -textvariable F -width 4
 label .cl -text "Degrees C:"
 entry .ec -textvariable C -width 4
 grid .fl .ef -sticky ew
 grid  .cl .ec -row 1 -sticky ew
 button .b -text "Exit" -command {exit}
 grid .b -row 2 -columnspan 2 -sticky ew

 #bindings
 bind .ef <Return> {set C [f2c $F]}
 bind .ec <Return> {set F [c2f $C]}

 wm title . "F2C"
----
Kinda ugly, but you get the idea...

If you never hang out in the chatroom, the discussion that followed
was both diverse and enlightening.