biomates at telefonica.net
Sun Mar 30 13:02:55 CDT 2008
Adam Majewski escribió:
> So the problem is he name of argument ?
> I have changed "t" to "theta" :
No, you can use the name you want, but you have to transform t to
something else, let's call it theta, which should be a true argument;
that is, the angle formed by the x-axis and the radius, or in other
words, the angle such that x=r*cos(theta) and y=r*sin(theta).
In my previous post, the Maxima code shows that the point associated to
%pi/2 doesn't rest on the y-axis.
> (%i1) e1:exp(theta*%i)/2-exp(2*theta*%i)/4;
> (%o1) %e^(%i*theta)/2-%e^(2*%i*theta)/4
> (%i2) r:abs(e1);
> (%i3) load(draw);
> (%i4) draw2d(nticks = 2000, xrange = [-2.5,0.5], yrange=[-1.5,1.5],
> color = blue, line_width= 3, polar(r,theta,0,2*%pi),grid=true)$
> but it gives the same curve.
Of course. You have only renamed the parameter, but this is not the key
>> If you want to draw a cardioid in polar form, use equation
>> (%i7) load(draw)$
>> (%i8) draw2d(polar(5*(1-cos(theta)), theta,0,2*%pi))$
> It works good but this is diffrent cardioid.
Sure, I chose coefficient 5 at random. My intention was to show how to
draw a cardioid in polar form, but I haven't looked at the
transformation to be performed.
Mario Rodriguez Riotorto
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