/usr/share/blt2.4/demos/spline.tcl is in blt-demo 2.4z-7ubuntu2.
This file is owned by root:root, with mode 0o755.
The actual contents of the file can be viewed below.
1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 21 22 23 24 25 26 27 28 29 30 31 32 33 34 35 36 37 38 39 40 41 42 43 44 45 46 47 48 49 50 51 52 53 54 55 56 57 58 59 60 61 62 63 64 65 66 67 68 69 70 71 72 73 74 75 76 77 78 79 80 81 82 83 84 | #!/usr/bin/wish
package require BLT
# --------------------------------------------------------------------------
# Starting with Tcl 8.x, the BLT commands are stored in their own
# namespace called "blt". The idea is to prevent name clashes with
# Tcl commands and variables from other packages, such as a "table"
# command in two different packages.
#
# You can access the BLT commands in a couple of ways. You can prefix
# all the BLT commands with the namespace qualifier "blt::"
#
# blt::graph .g
# blt::table . .g -resize both
#
# or you can import all the command into the global namespace.
#
# namespace import blt::*
# graph .g
# table . .g -resize both
#
# --------------------------------------------------------------------------
if { $tcl_version >= 8.0 } {
namespace import blt::*
namespace import -force blt::tile::*
}
source scripts/demo.tcl
option add *graph.Element.ScaleSymbols true
# test to show spline over-shooting
set tcl_precision 15
# Make and fill small vectors
vector x y
x seq 10 0 -0.5
y expr sin(x^3)
x expr x*x
x sort y
vector x2 y1 y2 y3
# make and fill (x only) large vectors
x populate x2 10
# natural spline interpolation
spline natural x y x2 y1
# quadratic spline interpolation
spline quadratic x y x2 y2
# make plot
graph .graph
.graph xaxis configure -title "x^2"
.graph yaxis configure -title "sin(y^3)"
.graph pen configure activeLine -pixels 5
.graph element create Original -x x -y y \
-color red4 \
-fill red \
-pixels 5 \
-symbol circle
.graph element create Natural -x x2 -y y1 \
-color green4 \
-fill green \
-pixels 3 \
-symbol triangle
.graph element create Quadratic -x x2 -y y2 \
-color blue4 \
-fill orange2 \
-pixels 3 \
-symbol arrow
table . .graph -fill both
Blt_ZoomStack .graph
Blt_Crosshairs .graph
Blt_ActiveLegend .graph
Blt_ClosestPoint .graph
Blt_PrintKey .graph
.graph grid on
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