How can I convert into new coordinates over a loop?
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Tom
el 25 de Oct. de 2018
Comentada: Star Strider
el 10 de Nov. de 2018
I am working with a set of vectors for a calculation: the vectors are obtained in spherical polar coordinates and I then need to convert them all so that they are in Cartesian coordinates.
Basically, I have a matrix where I store the positions of a set of N vectors in spherical polar coordinates. So the first row is composed of the theta component of each of the vectors, the second row is the phi component, and the third is the radial coordinate and I would then like to form a new matrix which is the same but now the first row is the x component, the second row is the y component, and the third row is the z component. However, when I try to create this new matrix, MATLAB just says that the dimensionality of the matrices doesn't work, for example:
r(1,1:10)= sin(alpha)*cos(phi);
where alpha and phi have been specified as the row vectors formed from the first and second rows of the original matrix.
The example above is if I were to try to create the first row of the new matrix for 10 vectors in the original spherical polar coordinates. I have looked it up and the advice is that I should basically make MATLAB to do it by looping over the combinations which are needed but I am unsure how to do this, could someone advise?
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Star Strider
el 25 de Oct. de 2018
4 comentarios
Star Strider
el 29 de Oct. de 2018
If your vectors are in the format that sph2cart expects, you should be able to use it without modification. The arguments can be ‘a scalar, vector, matrix, or multidimensional array.’
I do not understand the problem you are having with it.
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Tom
el 10 de Nov. de 2018
Editada: madhan ravi
el 10 de Nov. de 2018
7 comentarios
Star Strider
el 10 de Nov. de 2018
‘Basically I have a point which has a column vector in spherical coordinates on a sphere, then I take several such vectors for different points and slot them next to each other to make a matrix.’
Apparently, I still do not understand the problem you are having.
If your data vectors are gridded (have regularly-repeating patterns in the x- and y-coordinates), you can make them into a matrix using the reshape function first, then sph2cart.
If you simply have vectors in spherical coordinates that you want to change to Cartesian coordinates, you can do that easily enough with sph2cart.
You can then plot them using any function you wish. I use scatter3 in my example. Any other 3-D plotting function will work.
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