Mathematica Mathematica: plot and evaluate function of 2 variables

AI Thread Summary
The discussion focuses on plotting a function of two variables in Mathematica, specifically a radius function R(t, θ) that incorporates spherical harmonics. The user is trying to utilize "SphericalPlot3D" and "Manipulate" to visualize R as a function of θ and φ while adjusting time with a slider. They have provided their definitions for functions a(t) and b(t) and seek assistance in correctly implementing the plot. Another participant suggests adapting the provided code and breaking the problem into simpler tasks to identify any missing details. They recommend confirming the output of a basic spherical harmonic plot and testing simpler examples to troubleshoot the issue.
hasidim
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Hi all,

I am trying to evaluate and plot a function of two variable in mathematica.

Function:

Code:
R(t,\theta) = a(t) + b(t)*Y_n(\theta)

Where a(t) and b(t) are functions (that I have evaluated already), and Y is the spherical harmonic for a given n, and R is the radius.

In mathematica I am unsure how to evaluate and plot a function of two variables in spherical coordinates. I attempted to use "SphericalPlot3D" to plot R as a function of \theta and \phi, and "Manipulate" to add a slider to adjust the time but am having no luck.

Any help would be APPRECIATED!
 
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Is this something like what you are trying to do?

a[t_] := 2t; b[t_] := t^2; m = 1;(* < --- Substitute your functions here *)
R[t_, n_, m_, theta_, phi_] := a[t] + b[t]*SphericalHarmonicY[n, m, theta, phi]
Manipulate[SphericalPlot3D[R[t, n, m, theta, phi], {theta, 0, 2Pi}, {phi, 0, Pi}], {t, 0, 1}, {n, 0, 4, 1}]

Can you perhaps adapt this for what you need?
 
Bill Simpson said:
Is this something like what you are trying to do?

a[t_] := 2t; b[t_] := t^2; m = 1;(* < --- Substitute your functions here *)
R[t_, n_, m_, theta_, phi_] := a[t] + b[t]*SphericalHarmonicY[n, m, theta, phi]
Manipulate[SphericalPlot3D[R[t, n, m, theta, phi], {theta, 0, 2Pi}, {phi, 0, Pi}], {t, 0, 1}, {n, 0, 4, 1}]

Can you perhaps adapt this for what you need?

That is pretty similar to what I have tried... but, I'll try copying that and modifying it.

As usual, I suspect that I am missing just one small detail.
 
If your modification doesn't work then divide the problem into simpler tasks.
Confirm that
SphericalPlot3D[SphericalHarmonicY[1, 2, theta, phi]], {theta, 0, 2Pi}, {phi, 0, Pi}]
plot matches http://mathworld.wolfram.com/SphericalHarmonic.html
and substitute a few other values for the 1 and 2.
Then try a simpler Manipulate example using a Real and Integer value from the Help and confirm that works. That might uncover some of your missing details.
 

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