p = 30

e(x) = 10.0**((log10(x)*20-p)/10)

f(x) = (x-e(x) < 0)?0:(x-e(x))

d(x,y) = abs(x-f(y))

set ticslevel 0

set contour

set cntrparam bspline

set cntrparam points 10

set cntrparam order 10

set cntrparam levels incremental 0,5,100

set nosurface

set term table

set out 'data.out'

splot [1:1000] [1:1000] d(x,y)

set out

set term X11

set data style lines

plot 'data.out' index 0 t "100", \

        'data.out' index 3 notitle, \

        'data.out' index 6 t "70", \

        'data.out' index 9 notitle, \

        'data.out' index 12 t "60", \

        'data.out' index 15 notitle, \

        'data.out' index 18 t "10"