Generate points from given conic (A,B,C,D,E,F)

generate points from ellipse, hyperbola, circles, etc.

This function generates points from a generic conic given by
parameters A,B,C,D,E and F of its canonical equation:
A*x^2 + 2*B*x*y + C*y^2 + 2*D*x + 2*E*y + F = 0
The points can be noisy, and the power of the noise can be configured
with noise_power variable (std. deviation of gaussian noise).
The number of output points can be configured with number_points

xpoints are computed depending on the given domain and number_points
ypoitns are chosen to solve the canonic equation with xpoints.
If a combinations of parameters give a unsolvable condition on the real
field, the complex numbers are ignored. Thus, sometimes a smaller number
of points can be get.

EXAMPLES:
[x,y] = points_from_conic;
plot(x,y,'g.'); title('CIRCLE')

[x,y]=points_from_conic(3,4,5,3,0,1,[-10 0],200,0.0);
plot(x,y,'r*'); title('HYPERBOLA')

[x,y]=points_from_conic(1,0,1,0,0,-1,[-2 2],100,0.05);
plot(x,y,'bo'); title('Noisy ELLIPSE')