# set terminal png transparent nocrop enhanced font arial 8 size 420,320 # set output 'fit.15.png' set key bmargin center horizontal Right noreverse enhanced autotitles nobox set title "the scattered points, and the initial parameter" set xlabel "Temperature T [deg Cels.]" set ylabel "Density [g/cm3]" l(x) = y0 + m*x high(x) = mh*(x-Tc) + dens_Tc lowlin(x) = ml*(x-Tc) + dens_Tc curve(x) = b*tanh(g*(Tc-x)) density(x) = x < Tc ? curve(x)+lowlin(x) : high(x) h(x,y) = sqrt(r*r - (abs(x-x0))**2.2 - (abs(y-y0))**1.8) + z0 y0 = 0.2 m = -0.000943519626916798 FIT_CONVERGED = 1 FIT_NDF = 31 FIT_STDFIT = 5.38882119840539e-05 FIT_WSSR = 9.00221211159881e-08 ml = -0.00100003942457188 mh = -0.000831266464087347 dens_Tc = 1.02497044549157 Tc = 46.0899236389933 g = 3.85585054783351 b = 0.00153901241267826 FIT_LIMIT = 1e-05 r = 0.5 x0 = 0.1 z0 = 0.3 FIT_MAXITER = 50 splot 'hemisphr.dat' using 1:2:3, h(x,y) ## fit density(x) 'lcdemo.dat' via 'start.par'