hermann on Sun, 11 Feb 2024 01:44:28 +0100


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GP cross product?


I searched for "cross" and "vector product" in GP user's guide and found nothing.
I searched mailing lists unsuccessfully as well.

First I came up with this:

? cross=(a,b)->{m=matdet(Mat([[i,j,k]~,a~,b~]));[polcoef(m,1,i),polcoef(m,1,j),polcoef(m,1,k)]};
? cross([1,2,3],[2,3,4])
[-1, 2, -1]
?

Then by Wikipedia definition perhaps simpler:

? cross=(a,b)->[a[2]*b[3]-a[3]*b[2],a[3]*b[1]-a[1]*b[3],a[1]*b[2]-a[2]*b[1]];
? cross([1,2,3],[2,3,4])
[-1, 2, -1]
?

Is there something builtin in GP that can compute cross product of two vectors?


Regards,

Hermann.