/usr/share/doc/libplplot12/examples/tcl/x22.tcl is in plplot-tcl-dev 5.10.0+dfsg2-0.1ubuntu2.
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# $Id: x22.tcl 12806 2013-12-03 13:03:26Z andrewross $
#----------------------------------------------------------------------------
# Vector plot demo.
proc x22 {{w loopback}} {
matrix arrow_x f 6 = {-0.5, 0.5, 0.3, 0.5, 0.3, 0.5}
matrix arrow_y f 6 = {0.0, 0.0, 0.2, 0.0, -0.2, 0.0}
matrix arrow2_x f 6 = {-0.5, 0.3, 0.3, 0.5, 0.3, 0.3}
matrix arrow2_y f 6 = {0.0, 0.0, 0.2, 0.0, -0.2, 0.0}
circulation $w
set narr 6
set fill 0
$w cmd plsvect arrow_x arrow_y $fill
constriction $w 1
set fill 1
$w cmd plsvect arrow2_x arrow2_y $fill
constriction $w 2
constriction2 $w
$w cmd plsvect NULL NULL 0
potential $w
}
# Vector plot of circulation about the origin
proc circulation {w} {
set nx 20
set ny 20
set dx 1.0
set dy 1.0
set xmin [expr {-$nx/2*$dx}]
set xmax [expr {$nx/2*$dx}]
set ymin [expr {-$ny/2*$dy}]
set ymax [expr {$ny/2*$dy}]
matrix xg f $nx $ny
matrix yg f $nx $ny
matrix u f $nx $ny
matrix v f $nx $ny
# Create data - circulation around the origin.
for {set i 0} {$i < $nx} {incr i} {
set x [expr {($i-$nx/2+0.5)*$dx} ]
for {set j 0} {$j < $ny} {incr j} {
set y [expr {($j-$ny/2+0.5)*$dy}]
xg $i $j = $x
yg $i $j = $y
u $i $j = $y
v $i $j = [expr {-1.0*$x}]
}
}
# Plot vectors with default arrows
$w cmd plenv $xmin $xmax $ymin $ymax 0 0
$w cmd pllab "(x)" "(y)" "#frPLplot Example 22 - circulation"
$w cmd plcol0 2
$w cmd plvect u v 0.0 "pltr2" xg yg
$w cmd plcol0 1
}
# Vector plot of flow through a constricted pipe
proc constriction {w astyle} {
set nx 20
set ny 20
set dx 1.0
set dy 1.0
set xmin [expr {-$nx/2*$dx}]
set xmax [expr {$nx/2*$dx}]
set ymin [expr {-$ny/2*$dy}]
set ymax [expr {$ny/2*$dy}]
matrix xg f $nx $ny
matrix yg f $nx $ny
matrix u f $nx $ny
matrix v f $nx $ny
set Q 2.0
# Create data - circulation around the origin.
for {set i 0} {$i < $nx} {incr i} {
set x [expr {($i-$nx/2+0.5)*$dx} ]
for {set j 0} {$j < $ny} {incr j} {
set y [expr {($j-$ny/2+0.5)*$dy}]
xg $i $j = $x
yg $i $j = $y
set b [expr {$ymax/4.0*(3.0-cos($::PLPLOT::PL_PI*$x/$xmax))}]
if {abs($y) < $b} {
set dbdx [expr {$ymax/4.0*sin($::PLPLOT::PL_PI*$x/$xmax)*$::PLPLOT::PL_PI/$xmax*$y/$b}]
u $i $j = [expr {$Q*$ymax/$b}]
v $i $j = [expr {$Q*$ymax/$b*$dbdx}]
} else {
u $i $j = 0.0
v $i $j = 0.0
}
}
}
# Plot vectors with default arrows
$w cmd plenv $xmin $xmax $ymin $ymax 0 0
$w cmd pllab "(x)" "(y)" [format "#frPLplot Example 22 - constriction (arrow style %d)" $astyle]
$w cmd plcol0 2
$w cmd plvect u v -1.0 "pltr2" xg yg
$w cmd plcol0 1
}
proc transform { x y } {
global xmax
return [list \
[expr {$x}] \
[expr {$y / 4.0 * (3.0 - cos($::PLPLOT::PL_PI * $x / $xmax) ) }]]
}
# Vector plot of flow through a constricted pipe
# with a coordinate transform
proc constriction2 {w} {
set nx 20
set ny 20
set nc 11
set nseg 20
set dx 1.0
set dy 1.0
global xmax
set xmin [expr {-$nx/2*$dx}]
set xmax [expr {$nx/2*$dx}]
set ymin [expr {-$ny/2*$dy}]
set ymax [expr {$ny/2*$dy}]
$w cmd plstransform transform
matrix xg f $nx $ny
matrix yg f $nx $ny
matrix u f $nx $ny
matrix v f $nx $ny
set Q 2.0
# Create data - circulation around the origin.
for {set i 0} {$i < $nx} {incr i} {
set x [expr {($i-$nx/2+0.5)*$dx} ]
for {set j 0} {$j < $ny} {incr j} {
set y [expr {($j-$ny/2+0.5)*$dy}]
xg $i $j = $x
yg $i $j = $y
set b [expr {$ymax/4.0*(3.0-cos($::PLPLOT::PL_PI*$x/$xmax))}]
u $i $j = [expr {$Q*$ymax/$b}]
v $i $j = 0.0
}
}
matrix clev f $nc
for {set i 0} {$i < $nc} {incr i} {
clev $i = [expr {$Q + $i * $Q / ($nc - 1)}]
}
# Plot vectors with default arrows
$w cmd plenv $xmin $xmax $ymin $ymax 0 0
$w cmd pllab "(x)" "(y)" "#frPLplot Example 22 - constriction with plstransform"
$w cmd plcol0 2
$w cmd plshades u [expr {$xmin + $dx/2}] [expr {$xmax - $dx/2}] \
[expr {$ymin + $dy/2}] [expr {$ymax - $dy/2}] \
clev 0.0 1 1.0 0 NULL
$w cmd plvect u v -1.0 "pltr2" xg yg
$w cmd plpath $nseg $xmin $ymax $xmax $ymax
$w cmd plpath $nseg $xmin $ymin $xmax $ymin
$w cmd plcol0 1
$w cmd plstransform NULL
}
# Vector plot of the gradient of a shielded potential (see example 9)
proc potential {w} {
set nr 20
set ntheta 20
set nper 100
set nlevel 10
matrix xg f $nr $ntheta
matrix yg f $nr $ntheta
matrix u f $nr $ntheta
matrix v f $nr $ntheta
matrix z f $nr $ntheta
# Potential inside a conducting cylinder (or sphere) by method of images.
# Charge 1 is placed at (d1, d1), with image charge at (d2, d2).
# Charge 2 is placed at (d1, -d1), with image charge at (d2, -d2).
# Also put in smoothing term at small distances.
set rmax $nr
set eps 2.
set q1 1.
set d1 [expr {$rmax/4.}]
set q1i [expr {- $q1*$rmax/$d1}]
set d1i [expr {pow($rmax,2)/$d1}]
set q2 -1.
set d2 [expr {$rmax/4.}]
set q2i [expr {- $q2*$rmax/$d2}]
set d2i [expr {pow($rmax,2)/$d2}]
for {set i 0} {$i < $nr} {incr i} {
set r [expr {0.5 + $i}]
for {set j 0} {$j < $ntheta} {incr j} {
set theta [expr {(2. * $::PLPLOT::PL_PI / ($ntheta - 1.))*(0.5 + $j)}]
set x [expr {$r * cos($theta)}]
set y [expr {$r * sin($theta)}]
xg $i $j = $x
yg $i $j = $y
set div1 [expr {sqrt(pow($x-$d1,2) + pow($y-$d1,2) +
pow($eps,2))}]
set div1i [expr {sqrt(pow($x-$d1i,2) + pow($y-$d1i,2) + pow($eps,2))}]
set div2 [expr {sqrt(pow($x-$d2,2) + pow($y+$d2,2) +
pow($eps,2))}]
set div2i [expr {sqrt(pow($x-$d2i,2) + pow($y+$d2i,2) + pow($eps,2))}]
z $i $j = [expr {$q1/$div1 + $q1i/$div1i + $q2/$div2 + $q2i/$div2i}]
u $i $j = [expr {-$q1*($x-$d1)/pow($div1,3) - $q1i*($x-$d1i)/pow($div1i,3) -
$q2*($x-$d2)/pow($div2,3) - $q2i*($x-$d2i)/pow($div2i,3)}]
v $i $j = [expr {-$q1*($y-$d1)/pow($div1,3) - $q1i*($y-$d1i)/pow($div1i,3) -
$q2*($y+$d2)/pow($div2,3) - $q2i*($y+$d2i)/pow($div2i,3)}]
}
}
set xmin [xg 0 0]
set xmax $xmin
set ymin [yg 0 0]
set ymax $ymin
set zmin [z 0 0]
set zmax $zmin
for {set i 0} {$i < $nr} {incr i} {
for {set j 0} {$j < $ntheta} {incr j} {
if {[xg $i $j] < $xmin} { set xmin [xg $i $j] }
if {[xg $i $j] > $xmax} { set xmax [xg $i $j] }
if {[yg $i $j] < $ymin} { set ymin [yg $i $j] }
if {[yg $i $j] > $ymax} { set ymax [yg $i $j] }
if {[z $i $j] < $zmin} { set zmin [z $i $j] }
if {[z $i $j] > $zmax} { set zmax [z $i $j] }
}
}
$w cmd plenv $xmin $xmax $ymin $ymax 0 0
$w cmd pllab "(x)" "(y)" "#frPLplot Example 22 - potential gradient vector plot"
# Plot contours of the potential
set dz [expr {($zmax-$zmin)/$nlevel}]
matrix clevel f $nlevel
for {set i 0} {$i < $nlevel} {incr i} {
clevel $i = [expr {$zmin + ($i + 0.5)*$dz}]
}
$w cmd plcol0 3
$w cmd pllsty 2
$w cmd plcont z clevel "pltr2" xg yg
$w cmd pllsty 1
$w cmd plcol0 1
# Plot vectors with default arrows
$w cmd plcol0 2
$w cmd plvect u v 25.0 "pltr2" xg yg
$w cmd plcol0 1
# Plot the perimeter of the cylinder
matrix px f $nper
matrix py f $nper
set dtheta [expr {2.0*$::PLPLOT::PL_PI/($nper-1.0)}]
for {set i 0} {$i < $nper} {incr i} {
set theta [expr {$dtheta*$i}]
px $i = [expr {$rmax*cos($theta)}]
py $i = [expr {$rmax*sin($theta)}]
}
$w cmd plline $nper px py
}
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