set term svg enhanced fname "times,15"
set output "montgomery1.svg"

f(x) = sqrt((x**3 + 7 * x**2 + x)/3.)

set mxtics
set mytics
set linestyle 22 lc rgb "grey" lw 1.
set linestyle 19 lc rgb "red" lw 1.5
set grid linestyle 22
set key off
set samples 10000

set zeroaxis linestyle 22 lc rgb "#606060" lw 1
set xrange [-7:5]
set yrange [-10:10]

set xlabel "x"
set ylabel "y"

plot f(x) ls 19, -f(x) ls 19