SymPy: Symbolic Mathematics in Python

Post by tehsauce » Wed, Feb 28, 2024, 3:50 PM UTC

abricq wrote: post #11

Working in the field of robotics, I often have to write big vectors ( usually computed as the result of 3D transformations ) and then compute their Jacobian ( their derivative with respect to several state-variables ), which quickly becomes very nasty equations. I use sympy to (i) compute these big vectors, expressed in a very declarative way, (ii) compute the jacobian and (iii) export the results in C-code, immediat…

Post by abricq » Wed, Feb 28, 2024, 3:52 PM UTC

tehsauce wrote: post #51

abricq wrote: post #11

Working in the field of robotics, I often have to write big vectors ( usually computed as the result of 3D transformations ) and then compute their Jacobian ( their derivative with respect to several state-variables ), which quickly becomes very nasty equations. I use sympy to (i) compute these big vectors, expressed in a very declarative way, (ii) compute the jacobian and (iii) export the results in C-code, immediat…

Have you considered using jax? you can efficiently compute the jacobian (even using the gpu if you want) without leaving python at all. The api is also numpy compatible!

Post by analog31 » Wed, Feb 28, 2024, 3:55 PM UTC

exDM69 wrote: post #43

abricq wrote: post #11

Working in the field of robotics, I often have to write big vectors ( usually computed as the result of 3D transformations ) and then compute their Jacobian ( their derivative with respect to several state-variables ), which quickly becomes very nasty equations. I use sympy to (i) compute these big vectors, expressed in a very declarative way, (ii) compute the jacobian and (iii) export the results in C-code, immediat…

I've used SymPy in a very similar way, in my case it was some nasty derivatives that were needed for some orbital mechanics calculations. First write down the equations, then let SymPy do the laborious math part and turn the output into C code. I'm guessing this is why you don't see a lot of SymPy projects in the wild. It was used for some intermediate calculations, and the results were turned into the product's code…

Post by whizzter » Wed, Feb 28, 2024, 3:56 PM UTC

Post by abricq » Wed, Feb 28, 2024, 3:59 PM UTC

analog31 wrote: post #55

exDM69 wrote: post #43

Earlier quoted context omitted.

I've used SymPy in a very similar way, in my case it was some nasty derivatives that were needed for some orbital mechanics calculations. First write down the equations, then let SymPy do the laborious math part and turn the output into C code. I'm guessing this is why you don't see a lot of SymPy projects in the wild. It was used for some intermediate calculations, and the results were turned into the product's code…

There might be a better way, but my habit is to include the symbolic code as a comment in the C. I've thanked myself for doing this.