# List of functions used for tangent/normal 2D.
# An item in this list will be picked randomly at each exercise.
# Structure of item: multi-line.
# line 1 is function description.
# line 2 is derivative.
# line 3 is proportionality
# The rest is values for parameters c1, c2, etc.

:c1*x^c2+c3*y^c4
 c2*c1*x^(c2-1),c3*c4*y^(c4-1)
 1.5
 -1.5,-1.4,-1.3,-1.2,-1.1,-0.9,-0.8,-0.7,-0.6,0.6,0.7,0.8,0.9,1.1,1.2,1.3,1.4,1.5
 2,3,4
 -1.5,-1.4,-1.3,-1.2,-1.1,-0.9,-0.8,-0.7,-0.6,0.6,0.7,0.8,0.9,1.1,1.2,1.3,1.4,1.5
 2,3,4
:x^c1+y^c2+c3*x*y
c1*x^(c1-1)+c3*y, c2*y^(c2-1)+c3*x
1.2
 2,3
2,3,4
 -1.5,-1.4,-1.3,-1.2,-1.1,-0.9,-0.8,-0.7,-0.6,0.6,0.7,0.8,0.9,1.1,1.2,1.3,1.4,1.5
:c1*(x^2-c2)*(y^3-c3)
 2*c1*(y^3-c3)*x,3*c1*(x^2-c2)*y^2
 1
 -1.5,-1.4,-1.3,-1.2,-1.1,-0.9,-0.8,-0.7,-0.6,0.6,0.7,0.8,0.9,1.1,1.2,1.3,1.4,1.5
 -1.5,-1.4,-1.3,-1.2,-1.1,-0.9,-0.8,-0.7,-0.6,0.6,0.7,0.8,0.9,1.1,1.2,1.3,1.4,1.5
 -1.5,-1.4,-1.3,-1.2,-1.1,-0.9,-0.8,-0.7,-0.6,0.6,0.7,0.8,0.9,1.1,1.2,1.3,1.4,1.5
