Ah, there is an inconsistency in the above email. I am saying I want
dot-product, when in reality, what I want is an elementwise multiplication.
The same question still applies though. Is this something Sympy can do?
On Tuesday, 13 June 2023 at 06:28:52 UTC+2 Morten Olsen Lysgaard wrote:
> I am using Sympy for code generation.
>
> I would like to figure out the boundaries of what Sympy can do with
> respect to code generation for dynamically sized arrays.
>
> Let's say I would like to generate a simple dot-product C-function.
>
> void dot(int m, const double *A, const double *B, double *C) {
> for(int i=0; i<m; i++){
> C[i] = A[i]*B[i];
> }
> }
>
> Using `sympy.Matrix` I am able to generate a loop-unrolled version of this
> function for a fixed `m`, but this is not what I want. I want the general
> thing.
>
> I have been trying to get this working using `IndexedBase` et. al. but no
> luck. This is the closest I have gotten:
>
> import sys
> import sympy as sp
> import sympy.utilities.codegen
> from sympy.utilities import codegen
>
> m = sp.symbols('m', integer=True)
> i = sp.Idx('i', m)
> M = sp.IndexedBase('M', shape=(m))
> N = sp.IndexedBase('N', shape=(m))
> K = sp.IndexedBase('K', shape=(m))
> dot =sp.Eq(K[i], M[i]*N[i])
>
> rut_obj = codegen.make_routine('dot', dot, (m, M, N, K), language='C')
> rcg = codegen.CCodeGen()
> rcg.dump_c([rut_obj], sys.stdout, '')
>
> But it outputs spurious loops which I can not explain, and will not
> compute the correct answer:
>
> void dot(int m, double *M, double *N, double *K) {
> for (int i=0; i<m; i++){
> K[i] = 0;
> }
> for (int i=0; i<m; i++){
> for (int i=0; i<m; i++){
> K[i] = K[i] + M[i]*N[i];
> }
> }
> }
>
> Is there anyone that are able to generate a simple dot-product function
> like the one in the top of my email using Sympy code generation?
>
> Any help would be greatly appreciated!
>
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