-0.02 .3 setxrange
-2 22 setyrange
1000 setxunit
10 setyunit
[.1 10 .01 1 .005 .5] {orange} Quadrillage

.8 setlinewidth
traceaxes
axesarrow

[1 10 20] {ymark} apply
[.01 0.1 0.2] {xmark} apply

/a .12 def
/V {neg a div Exp 20 mul} def
/T {-20 mul a div 20 add} def

0 xmax {V} Courbe
0 .12 {T} Courbe

setTimesItalic
   (y) 0 ymax (0 -10) bltext
   (t) xmax 0 (-20 0) ultext
setTimes
   (en volts) 0 ymax (0 -10) brtext
   (en secondes) xmax 0 dltext
   
#tex# $y = V (t)$
.12 10 brtexlabel

.2 setlinewidth
.12 10 .1 dup V (-) line