#

# Demo of plotting piecewise functions

#

unset border

set key center top reverse Left

set xzeroaxis

set yzeroaxis

set xtics axis out scale 1,8

set xtics add  (1.00000 1, 6.28319 1)

set ytics axis

set title "Piecewise function sampling" font ",15"

set xrange [ -2 : 10 ] noreverse nowriteback

plot sample [*:1] x, [1:2.*pi] cos(x), [2.*pi:10] (x-8)**2

pause -1 "Hit <cr> to continue"

reset

#

# This example taken from 

# http://amca01.wordpress.com/2012/05/29/a-piecewise-polynomial-approximation-to-the-normal-cdf/

# Original approximation from John Hoyt (1962), The American Statistician 22:25-26.

#

set termopt enhanced

set termopt dash

save_encoding = GPVAL_ENCODING; set encoding utf8

set title "Piecewise approximation to the\nNormal Cumulative Distribution Function"

set format "%.1f"

set key left Left reverse invert

set style data lines

set xtics nomirror

set xrange [ 0   : 4 ]

set yrange [ 0.5 : 1.1 ]

set style line 1 lt 0 lw 3

set style line 2 lt 0 lw 3 lc rgb "red"

part1(x) = 0.5 + (9.*x-x**3)/ 24.

part2(x) = 1.0 + (x-3.0)**3 / 48.

part1 = "part1: for x < 1  norm(x) ≈  ½ + (9x-x^3) / 24"

part2 = "part2: for x > 1  norm(x) ≈   1 +  (x-3)^3 / 48"

set label 1 at 1.0, 0.62

set label 1 "plot norm(x),  [0:1] part1(x),  [1:4] part2(x)"

set arrow 1 from 1.,.7 to 1.,.9 nohead

plot norm(x) lt -1, \

     [1:4] part2(x) ls 2 title part2, \

     [0:1] part1(x) ls 1 title part1

pause -1 "Hit <cr> to continue"

set termopt solid

reset

set border 16

unset xtics

unset ytics

set xyplane at 0

set style data lines

set key center at screen 0.5, screen 0.15

set title font ",15"

set title "Piecewise function of one parameter in 3D"

splot [-2:2][-2:2] sample \

   [h=1:5]   '+' using (cos(h)):(sin(h)):(h) lw 2, \

   [h=5:10]  '+' using (cos(h)):(sin(h)):(h) lw 4, \

   [h=10:15] '+' using (cos(h)):(sin(h)):(h) lw 2

pause -1 "Hit <cr> to continue"

set encoding save_encoding

reset