Mathematica Plotting arbitrary constants in mathematica

[kraigandrews]

How do you plot arbitrary constants in mathematica? for example r(psi)=a(1-eCos(psi)), where a and e are some constant.

Thanks in advance for the help.

 

[Dale]

Well, you cannot plot a function with arbitrary constants. Where would the computer draw the line? However, what you can do is do a Plot inside a Manipulate, like this:

Manipulate[Plot[a (1 - e Cos[psi]), {psi, -1, 1}], {{a, 1}, -2, 2}, {{e, 1}, -2, 2}]

 

[kraigandrews]

OK thanks.

 

[Simon_Tyler]

Some constants can be absorbed into variables by defining dimensionless variables.
This basically treats the constant as the "natural scale" for that dimension.

In your example, you can define the dimensionless, s = r/a
But e is dimensionless and can't really be absorbed anywhere.

So

Manipulate[ Plot[ 1 - e Cos[psi], {psi, -1, 1}, AxesLabel->{"psi","s=r/a"}], {{e,1}, -2, 2}]