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#
# Elliptic integrals of the third kind
#
save_encoding = GPVAL_ENCODING
set encoding utf8
set title "Complete elliptic integral of the third kind EllipticPi(n,k)"
set key reverse left Left
set key title "Π(n,k) = {/*2 ∫@_{/*0.5 0}^{/*.5 π/2}}"\
."{/:Italic [1-nsin^2(t)]^{-1} sqrt(1-k^2sin^2(t))^{-1} dt}\n"
set border 3
set margins 10,10,-1,4
set sample 250
set xrange [0:1]
set xtics 0.1 format "%.1f" nomirror
set yrange [0:6]
set ytics 1 nomirror
set xlabel "{/:Italic k}"
plot EllipticPi(0.5,x) with lines lw 2 title "n = 0.5", \
EllipticPi(0.0,x) with lines lw 2 title "n = 0", \
EllipticPi(-1.,x) with lines lw 2 title "n = -1", \
EllipticPi(-3.,x) with lines lw 2 title "n = -3", \
EllipticPi(-10.,x) with lines lw 2 lc "brown" title "n = -10"
pause -1 "<cr> to continue"
set title "Complete elliptic integrals of the first and second kinds"
set key notitle invert top center spacing 2
set xtics 0.5
set xlabel "x"
set xrange [-1:1]
set yrange [1:3]
plot EllipticE(x) lw 2 title "\nEllipticE(x)={/*1.5 ∫@_{/*0.5 0}^{/*.5 π/2}}{/:Italic sqrt(1-k^2sin^2(t)) dt}\n",\
EllipticK(x) lw 2 title "\nEllipticK(x)={/*1.5 ∫@_{/*0.5 0}^{/*.5 π/2}}{/:Italic sqrt(1-k^2sin^2(t))^{-1} dt}\n"
pause -1 "<cr> to continue"
reset
set encoding save_encoding
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