numericalImageDim(F, I, p)
numericalImageDim(F, I)
The method computes the dimension of the image of a variety numerically. Even if the source variety and map are projective, the affine (Krull) dimension is returned. This ensures consistency with dim.
The following example computes the affine dimension of the Grassmannian $Gr(2,4)$ of $P^1$'s in $P^3$, under its Plücker embedding in $P^5$.
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For comparison, here is how to do the same computation symbolically.
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Next is an example where direct symbolic computation fails to terminate quickly. Part of the Alexander-Hirschowitz theorem states that the $14$th secant variety of the $4$th Veronese of $P^4$ has affine dimension $69$, rather than the expected $14*4 + 13 + 1 = 70$. See J. Alexander, A. Hirschowitz, $Polynomial interpolation in several variables$, J. Alg. Geom. 4(2) (1995), 201-222. We numerically verify this below.
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The object numericalImageDim is a method function with options.