# set terminal svg size 600,400 dynamic enhanced fname 'arial'  fsize 10 mousing name "transparent_2" butt solid 
# set output 'transparent.2.svg'
set clip two
set style fill  transparent solid 0.50 noborder
set key title "Gaussian Distribution"
set key inside left top vertical Left reverse enhanced autotitles nobox
set key noinvert samplen 1 spacing 1 width 0 height 0 
set style function filledcurves y1=0
set title "Transparent filled curves" 
set xrange [ -5.00000 : 5.00000 ] noreverse nowriteback
set yrange [ 0.00000 : 1.00000 ] noreverse nowriteback
unset colorbox
Gauss(x,mu,sigma) = 1./(sigma*sqrt(2*pi)) * exp( -(x-mu)**2 / (2*sigma**2) )
d1(x) = Gauss(x, 0.5, 0.5)
d2(x) = Gauss(x,  2.,  1.)
d3(x) = Gauss(x, -1.,  2.)
GPFUN_Gauss = "Gauss(x,mu,sigma) = 1./(sigma*sqrt(2*pi)) * exp( -(x-mu)**2 / (2*sigma**2) )"
GPFUN_d1 = "d1(x) = Gauss(x, 0.5, 0.5)"
GPFUN_d2 = "d2(x) = Gauss(x,  2.,  1.)"
GPFUN_d3 = "d3(x) = Gauss(x, -1.,  2.)"
plot d1(x) fs solid 1.0 lc rgb "forest-green" title "μ =  0.5 σ = 0.5",      d2(x) lc rgb "gold" title "μ =  2.0 σ = 1.0",      d3(x) lc rgb "red" title "μ = -1.0 σ = 2.0"