25 setxunit
7.5 setborder
90 setangle_repere
-5 5 setxrange
-5 5 setyrange
1 1 settkstep
.5 .5 setsubtkstep
2 2 setmkstep
ticks
subticks
marks
traceaxes
axesarrow
0.75 setlinewidth
continu
bleu
/X {settvar
#rpn#   Cos(t)*(2^(1/2)*Cos(t)+1)
} def
/Y {settvar
#rpn#   Sin(t)*(2^(1/2)*Cos(t)-1)
} def
  10 neg  10 {X} {Y} Courbeparam