Help on Jacobian Matrix for Cartesian to Spherical

In summary, the conversation discusses the process of finding the Jacobian matrix for the transformation from spherical to cartesian coordinates and vice versa. The inverse matrix is needed for the cartesian to spherical transformation, but the direct matrix is not readily available online. The author shares their attempts at finding the direct matrix, but realizes the problem lies in the dependence of theta and phi on y and z. They suggest finding the matrix inverse as a simpler alternative.
  • #1
WannabeNewton
Science Advisor
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Hi. First off I don't know if this is the right topic area for this question so I'm sorry if it isn't.
So my current situation is that I can find the jacobian matrix for a transformation from spherical to cartesian coordinates and then take the inverse of that matrix to get the mapping from cartesian to spherical. But this inverse matrix has sin, cos terms etc. I was hoping if someone could give me the jacobian matrix for cartesian to spherical directly using: the functions of the cartesian coordinates to give the spherical coordinates. I cannot find it anywhere online as every site simply has it in the inverse matrix form and I have no way of really checking myself.
 
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  • #2
I was wondering the same thing--or maybe the opposite. This page for instance, gives the jacobian matrix:
[tex]\left[\begin{array}{ccc}
sin(\theta)cos(\phi) & sin(\theta)sin(\phi) & cos(\theta) \\ r cos(\theta)cos(\phi) & r cos(\theta)sin(\phi) & -r sin(\theta) \\ -r sin(\theta)sin(\phi) & r sin(\theta)cos(\phi) & 0
\end{array}\right][/tex]
which the author finds by calculating the total derivative for the spherical coordinates.I tried to do the same thing going the other direction and got:
[tex]
\frac{\partial}{{\partial}x} =\frac{{\partial}r}{{\partial}x}\frac{\partial}{{\partial}r} + \frac{{\partial}\theta}{{\partial}x}\frac{{\partial}}{{\partial}\theta}+\frac{{\partial}\phi}{{\partial}x}\frac{{\partial}}{{\partial}\phi}
=\frac{1}{sin(\theta)cos(\phi)}\frac{\partial}{{\partial}r}+\frac{1}{r cos(\theta)cos(\phi)}\frac{\partial}{{\partial}\theta}+\frac{-1}{r sin(\theta)sin(\phi)}\frac{\partial}{{\partial}\phi}
[/tex]
which is not what you would calculate using the inverse matrix. I suspect the problem is that I used [tex]\frac{{\partial}r}{{\partial}x}=\frac{1}{\frac{{\partial}x}{{\partial}r}}[/tex]
After finding this thread I think the reason this doesn't work is because phi and theta depend on y and z, so you need explicitly figure out that dependence:
[tex]
x=r sin(\theta)cos(\phi)=r sin(arcsin(z/r))cos(arcsin(\frac{y}{r sin(\theta)}))=\sqrt{r^2-z^2}\sqrt{1-\frac{y^2}{r^2-z^2}}=\sqrt{r^2-z^2-y^2}
[/tex]
Now you can take the derivative of this with respect to r while holding z and y constant and then make some substitutions and take the reciprocal. Then repeat for the other partials involved...

Presumably there's an easier way to do this since finding the matrix inverse works just as well and I don't think it would require as much work
 

1. What is the purpose of the Jacobian matrix in converting from Cartesian to Spherical coordinates?

The Jacobian matrix is used to calculate the derivatives of the spherical coordinates with respect to the Cartesian coordinates. It helps to determine how a small change in the Cartesian coordinates affects the spherical coordinates, and vice versa.

2. How is the Jacobian matrix calculated for the conversion?

The Jacobian matrix is calculated by taking the partial derivatives of the spherical coordinates (radius, azimuth angle, and polar angle) with respect to the Cartesian coordinates (x, y, and z). These partial derivatives are then arranged in a matrix form.

3. Why is the Jacobian matrix important in multivariable calculus?

The Jacobian matrix is important in multivariable calculus because it helps to solve problems involving multiple variables and their relationships. It is also used in transformations between different coordinate systems, such as Cartesian to Spherical coordinates.

4. Can the Jacobian matrix be used for other coordinate conversions?

Yes, the Jacobian matrix can be used for other coordinate conversions besides Cartesian to Spherical. It is a versatile tool in multivariable calculus and can be applied to many different types of coordinate systems.

5. Are there any limitations or drawbacks to using the Jacobian matrix?

One limitation of using the Jacobian matrix is that it assumes smooth and continuous functions, which may not always be the case in real-world applications. Additionally, it can become computationally complex for higher dimensions and more complicated coordinate systems.

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