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proc x03 {{w loopback}} {
set twopi [expr {2. * $::PLPLOT::PL_PI}]
# Set up viewport and window, but do not draw box
$w cmd plenv -1.3 1.3 -1.3 1.3 1 -2
# Draw circles for polar grid
set ni 10
set nj 360
set nj1 [expr {$nj + 1}]
set dr [expr {1. / $ni}]
set dtheta [expr {$twopi / $nj}]
matrix xj f $nj1
matrix yj f $nj1
for {set i 1} {$i <= $ni} {incr i} {
$w cmd plarc 0.0 0.0 [expr {0.1 * $i}]] [expr {0.1 * $i}] 0.0 360.0 0.0 0
}
# Draw radial spokes for polar grid and write labels for angle
$w cmd plcol0 2
for {set j 0} {$j <= 11} {incr j} {
set theta [expr {$j * $twopi / 12.}]
set xg [expr {cos($theta)}]
set yg [expr {sin($theta)}]
$w cmd pljoin 0.0 0.0 $xg $yg
set theta_deg [expr {$theta*360./$twopi}]
if {$theta_deg < 9.99} {
set offset 0.45
} elseif {$theta_deg < 99.9} {
set offset 0.30
} else {
set offset 0.15
}
# Slightly off zero to avoid floating point logic flips at 90 and 270 deg.
if {$xg >= -0.00001} {
set dx $xg
set dy $yg
set just [expr {-$offset}]
} else {
set dx [expr {-$xg}]
set dy [expr {-$yg}]
set just [expr {1. + $offset}]
}
set label [expr {round($theta*360./$twopi)}]
# N.B. cannot get this command to give same postscript output. Also visual
# inspection shows 90 deg label jumping around slightly compared to python
# and C front ends. No idea why (AWI comment).
$w cmd plptex $xg $yg $dx $dy $just $label
}
# Draw the graph
set npts 360
set npts1 [expr {$npts+1}]
set dtheta [expr {$twopi / $npts}]
matrix x f $npts1
matrix y f $npts1
for {set j 0} {$j <= $npts} {incr j} {
set theta [expr {$j * $dtheta}]
set r [expr {sin(5 * $theta)}]
x $j = [expr {$r * cos($theta)}]
y $j = [expr {$r * sin($theta)}]
}
$w cmd plcol0 3
$w cmd plline x y
$w cmd plcol0 4
$w cmd plmtex "t" 2.0 0.5 0.5 "#frPLplot Example 3 - r(#gh)=sin 5#gh"
# Restore defaults
# $w cmd plcol0 1
}
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