The plotter
# --------------------------
# params
# --------------------------
# title
# canvas width & height
# delay between plots
# x = f(t)
# plot expression
# initial & final times
# accuracy
array set params \
{
title {sin(x)}
width 400
height 240
delay 50
x {$t / 50.}
plot {sin($x)}
t0 0
# {t1 < t0: non-stop scrolling}
t1 -1
accuracy 1.e-2
}
# --------------------------
# plotting
# --------------------------
# computed heights
set h $params(height)
set h1 [expr {int($h * 0.5)}] ;# canvas mid-height
set h2 [expr {$h1 + 1}]
set h3 [expr {int($h * 0.4)}] ;# graph mid-height
# canvas & bindings
canvas .c -width $params(width) -height $h \
-xscrollincrement 1 -bg beige
pack .c
bind . <Destroy> { exit }
# plotting
wm title . $params(title)
.c xview scroll $params(t0) unit
set t $params(t0)
while {$t != $params(t1)} \
{
update
after $params(delay)
set x [expr $params(x)]
set vv [expr $params(plot)]
set v [expr {int($vv * $h3) + $h1}]
if {abs($vv) < $params(accuracy)} \
{
.c create text $t 0 -anchor n -text $t -fill gray
.c create line $t 0 $t $h -fill gray
}
.c create line $t $h1 $t $h2 -fill gray
.c create rectangle $t $v $t $v
incr t
if {$t > $params(width)} { .c xview scroll 1 unit }
}Another set of parameters
array set params \
{
title {x^3 - x}
width 400
height 240
delay 50
x {$t / 100.0}
plot {pow($x,3) - $x}
t0 -200
t1 200
accuracy 1.e-6
}See also
- See A Graph plotter for a different approach.
- Histogram Plotter
- Fun with functions
- Plotting data