# 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*cos(c3*x)+c2*sin(c4*y)
-c1*c3*sin(c3*x),c2*c4*cos(c4*y)
 1.2
 -0.8,-0.7,-0.6,-0.5,-0.4,0.4,0.5,0.6,0.7,0.8
 -0.8,-0.7,-0.6,-0.5,-0.4,0.4,0.5,0.6,0.7,0.8
 -1.4,-1.3,-1.2,-1.1,-0.9,-0.8,-0.7,-0.6,-0.5,-0.4,-0.3,0.3,0.4,0.5,0.6,0.7,0.8,0.9,1.1,1.2,1.3,1.4
 -1.4,-1.3,-1.2,-1.1,-0.9,-0.8,-0.7,-0.6,-0.5,-0.4,-0.3,0.3,0.4,0.5,0.6,0.7,0.8,0.9,1.1,1.2,1.3,1.4
:c1*cos(c2*x*y)
-c1*c2*y*sin(c2*x*y),-c1*c2*x*sin(c2*x*y)
 1.2
 -0.8,-0.7,-0.6,-0.5,-0.4,0.4,0.5,0.6,0.7,0.8
 -0.8,-0.7,-0.6,-0.5,-0.4,0.4,0.5,0.6,0.7,0.8
 :cos(c2*x)*sin(c3*y)
-sin(c3*y)*c2*sin(c2*x),cos(c2*x)*c3*cos(c3*y)
 1.2
 -4,-3,-2,-1,1,2,3,4
 -4,-3,-2,-1,1,2,3,4
