set term pngcairo size 1000, 800
set grid
f1(x) = a1*x
f2(x) = a2*x
f3(x) = a3*x+b3
f4(x) = a4*x+b4


set output 'ex4.png'
fit f1(x) 'DSilnViV0_Tconst1.plot' using 1:2 via a1
fit f2(x) 'DSilnViV0_Tconst4.plot' using 1:2 via a2

set title "Зависимость                          при разных температурах"
set xlabel "ед."
set ylabel "S_i, Дж/К"

plot	'DSilnViV0_Tconst1.plot' notitle lc 0 pt 1 lw 2,	\
	f1(x) title "           (T = 289 K)" lc rgb "magenta",\
	'DSilnViV0_Tconst4.plot' notitle lc 0 pt 1 lw 2,	\
	f2(x) title "           (T = 3232.5 K)" lc rgb "red"


set output 'ex1.png'
unset label
set title "зависимости P(V), PV(V) в изотермическом процессе при разных температурах"
set xlabel "V, м^3"
set ylabel "P, Па"
set y2tics
set y2label "PV, Па * м^3"
set key top left
set yrange[950:1200]
set y2range[35000:45000]

plot 	'PV1.plot' notitle axis x1y1 lc 0 pt 1 lw 2,	\
	'PV1.plot' with lines axis x1y1 smooth csplines title "P(V) (T = 289 K)" lc rgb "orange", \
	'PVV1.plot' notitle axis x1y2 lc 0 pt 1 lw 2, \
	'PVV1.plot' with lines axis x1y2 smooth csplines title "PV(V) (T = 289 K)" lc rgb "magenta", \
	'PV4.plot' notitle axis x1y1 lc 0 pt 1 lw 2,	\
        'PV4.plot' with lines axis x1y1 smooth csplines title "P(V) (T = 323.5 K)" lc rgb "red", \
        'PVV4.plot' notitle axis x1y2 lc 0 pt 1 lw 2, \
        'PVV4.plot' with lines axis x1y2 smooth csplines title "PV(V) (T = 323.5 K)" lc rgb "green"


set output 'ex23_mnk.png'
fit f1(x) 'DSilnTiT0_Pconst.plot' using 1:2 via a1
fit f2(x) 'DSilnTiT0_Vconst.plot' using 1:2 via a2

unset xrange
unset yrange
unset x2tics
unset y2label
unset y2range
set title "зависимости                      при P = const, V = const"
set xlabel "ед."
set ylabel "S_i, Дж/К"

set label sprintf("(A)_P = %.4g\n (A)_V = %.4g", a1, a2) at graph 0.2, 0.9 front boxed
plot	'DSilnTiT0_Vconst.plot' notitle lc rgb "green" pt 1 lw 3,\
	'DSilnTiT0_Pconst.plot' notitle lc rgb "magenta" pt 2 lw 3,\
	f2(x) title "V = const" lc rgb "green",\
	f1(x) title "P = const" lc rgb "magenta"
unset label

set output 'ex2.png'
set title "Зависимость V/T от V при P = const"
set xlabel "V, м^3"
set ylabel "V/T, м^3/К"
set yrange[0.13:0.14]

plot	'VTV.plot' notitle lc 0 pt 1 lw 2,\
	'VTV.plot' title "V/T (V)" lc rgb "magenta" with lines smooth csplines



set output 'ex3.png'

set title "Зависимость P/T (P) при V = const (по большей части)"
set xlabel "P, Па"
set ylabel "P/T, Па/K"
set yrange[3:3.2]
set xrange [980:1001]
set label "график идёт так потому, что\nпробка выдвинулась и\nобъём увеличился" at graph 0.6, 0.7 boxed

plot	'PTP.plot' notitle lc 0 pt 1 lw 2,\
        'PTP.plot' title "P/T (P)" lc rgb "magenta" with lines smooth path