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D.15.10.2 signature
Procedure from library surfacesignature.lib (see surfacesignature_lib).
- Usage:
- signature(N,f); N = integer, f = reduced poly in 2 variables,
# empty or 1,2,3
- if # is empty or #[1] = 2 then resolution of singularities is used
- if #[1] = 1 then f has to be analytically irreducible and Puiseux
expansions are used
- if #[1] = 3 then spectral pairs are used
- Return:
- signature of surface singularity defined by z^N + f(x,y) = 0
Example:
| LIB "surfacesignature.lib";
ring r = 0,(x,y),dp;
int N = 3;
poly f = x15-21x14+8x13y-6x13-16x12y+20x11y2-x12+8x11y-36x10y2
+24x9y3+4x9y2-16x8y3+26x7y4-6x6y4+8x5y5+4x3y6-y8;
signature(N,f,1);
==> -92
signature(N,f,2);
==> -92
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