Singular Manual: chAllInv

| #### D.15.4.11 chAllInv Procedure from library `chern.lib` (see chern_lib). Usage: chAllInv(l); l a list of polynomials Return: list of polynomials Purpose: procedure inverse to chAll(), computes the list of Chern classes from the list of terms of positive degree of the Chern character Note: makes sense only for a list of polynomials Example:
    LIB "chern.lib";
    // first 3 Chern classes in terms of the first 3 terms
    // of the Chern character Chern  ch(1), ch(2), ch(3):
    ring r = 0, (ch(1..3)), dp;
    list l=(ch(1..3));
    print(chAllInv(l));
    ==> [1]:
    ==>    ch(1)
    ==> [2]:
    ==>    1/2*ch(1)^2-ch(2)
    ==> [3]:
    ==>    1/6*ch(1)^3-ch(1)*ch(2)+2*ch(3)
    // let's see that chAllInv() is inverse to chAll()
    print( chAll( chAllInv(l) ) );
    ==> [1]:
    ==>    ch(1)
    ==> [2]:
    ==>    ch(2)
    ==> [3]:
    ==>    ch(3)

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