# To generate the last frame of derivative curve.
# Author: Ika, 2013/9/6
set term pngcairo size 800,600 enhanced font 'Times,12'
set output 'derv05.png'
set multiplot
set xrange [-1:5]
set yrange [-1:25]
set label " x -> 0" at 1,20 font "Times,64"
set xzeroaxis lt -1 lc rgb "black" lw 1
set yzeroaxis lt -1 lc rgb "black" lw 1
# Draw the quadratic function
set key off
plot x*x lc rgb "blue" lw 3
x=1
k=x+1
plot k*(x-1)+1 lc rgb "red" lw 2
plot 2x lc rgb "yellow" lw 3
unset multiplot
set term x11
set output