See Fun with functions for a quite improved version (still little ;-)
Richard Suchenwirth -- Of course there is BLT, but Tcl is just such a great wheel reinvention tool ;-) Somebody asked on comp.lang.tcl whether there's software for plotting functions, and I just needed a little challenge. So here it is: fun2points tabulates x/y values for a given function, plotpoints draws, scales, and moves such a tabulated function (or whatever other x/y coordinates - stock quotes over time?) on a given canvas, and some wrapping lines as usage example. Sheer fun...
#!/bin/sh
# next lines restarts \
exec wish "$0" ${1+"$@"}
proc fun2points {fun args} {
array set opt {
-from -4.0 -to 4.0 -step .1
}
array set opt $args
set res [list]
for {set x $opt(-from)} {$x <= $opt(-to)} {set x [expr {$x+$opt(-step)}]} {
if {![catch {expr $fun} y]} {lappend res $x $y}
}
set res
}
proc plotpoints {w points args} {
eval $w create line $points $args
set maxx [set minx [lindex $points 0]]
set maxy [set miny [lindex $points 1]]
foreach {x y} $points {
if {$x<$minx} {set minx $x}
if {$x>$maxx} {set maxx $x}
if {$y<$miny} {set miny $y}
if {$y>$maxy} {set maxy $y}
}
$w create line $minx 0 $maxx 0
$w create line 0 $miny 0 $maxy
set xfac [expr 0.95*[$w cget -width]/($maxx-$minx)]
set yfac [expr 0.95*[$w cget -height]/($maxy-$miny)]
$w scale all 0 0 $xfac -$yfac
foreach {minxc minyc} [$w bbox all] break
$w move all [expr -$minxc+5] [expr -$minyc+5]
}
set fun [lindex $argv 0]
pack [canvas .c]
plotpoints .c [fun2points $fun] -fill red
wm title . $fun
# usage example: funplot.tcl 'sin($x)'Here are actually some problems. This script probably runs on UNIX, but not on Windows 2000. I had to change it to the following form to be able to run it from the wish.
#!/bin/sh
# next lines restarts \
# the following line doesn't do anything under windows, does it?
# exec wish "$0" ${1+"$@"}
proc fun2points {fun args} {
array set opt {
-from -4.0 -to 4.0 -step .1
}
array set opt $args
set res [list]
for {set x $opt(-from)} {$x <= $opt(-to)} {set x [expr {$x+$opt(-step)}]} {
# i had to exchange the following line:
# if {![catch {expr $fun} y]} {lappend res $x $y}
set func $fun
append func ($x)
lappend res $x [expr $func]
}
set res
}
proc plotpoints {w points args} {
eval $w create line $points $args
set maxx [set minx [lindex $points 0]]
set maxy [set miny [lindex $points 1]]
foreach {x y} $points {
if {$x<$minx} {set minx $x}
if {$x>$maxx} {set maxx $x}
if {$y<$miny} {set miny $y}
if {$y>$maxy} {set maxy $y}
}
$w create line $minx 0 $maxx 0
$w create line 0 $miny 0 $maxy
set xfac [expr 0.95*[$w cget -width]/($maxx-$minx)]
set yfac [expr 0.95*[$w cget -height]/($maxy-$miny)]
$w scale all 0 0 $xfac -$yfac
foreach {minxc minyc} [$w bbox all] break
$w move all [expr -$minxc+5] [expr -$minyc+5]
}
proc funplot {argv} {
set fun [lindex $argv 0]
if {[winfo exists .c]} {destroy .c}
pack [canvas .c]
plotpoints .c [fun2points $fun] -fill red
wm title . $fun
}
# i also had to exchange the usage
# usage example: funplot sinThere is something very weird also: x should run up to 4.0 in this example, but it runs only to 3.9 :-(
Does anyone understand this, please? Yes - comparing doubles is a real problem. Since I just wanted to cover the range from -Pi to +Pi, I didn't look that hard, but you're right, and can isolate the problem to
expr {3.9+.01>1.0}which returns 1. so a cleaner test condition would have been
for ... {($x-$opt(-to))<0.00001} ...or another delta that bridges the gap between real and evident - RS
BLT is at http://www.tcltk.com/blt/ . See also emu-graph, padgraph at http://www.shlrc.mq.edu.au/~steve/tcl