Top
Back: parameterSubstitute
Forward: randomPolyInT
FastBack:
FastForward:
Up: tropical_lib
Top: Singular Manual
Contents: Table of Contents
Index: Index
About: About this document

D.13.6.32 tropicalSubst

Procedure from library tropical.lib (see tropical_lib).

Usage:
parameterSubstitute(f,N,L); f poly, N int, L list

Assume:
f is a polynomial in Q(t)[x_1,...,x_k]
and L is a list of the form var(i_1),poly_1,...,v(i_k),poly_k

Return:
list, the list is the tropical polynomial which we get from f by replacing the i-th variable be the i-th polynomial but in the i-th polynomial the parameter t is replaced by t^1/N

Example:
 
LIB "tropical.lib";
ring r=(0,t),(x,y),dp;
poly f=t2x+1/t*y-1;
tropicalSubst(f,2,x,x+t,y,tx+y+t2);
// The procedure can be used to study the effect of a transformation of
// the form x -> x+t^b, with b a rational number, on the tropicalisation and
// the j-invariant of a cubic over the Puiseux series.
f=t7*y3+t3*y2+t*(x3+xy2+y+1)+xy;
// - b=3/2, then the cycle length of the tropical cubic equals -val(j-inv)
list g32=tropicalSubst(f,2,x,x+t3,y,y);
tropicalJInvariant(g32);
// - b=1, then it is still true, but only just ...
list g1=tropicalSubst(f,1,x,x+t,y,y);
tropicalJInvariant(g1);
// - b=2/3, as soon as b<1, the cycle length is strictly less than -val(j-inv)
list g23=tropicalSubst(f,3,x,x+t2,y,y);
tropicalJInvariant(g23);


Top Back: parameterSubstitute Forward: randomPolyInT FastBack: FastForward: Up: tropical_lib Top: Singular Manual Contents: Table of Contents Index: Index About: About this document
            User manual for Singular version 4.3.2, 2023, generated by texi2html.