poly.spad line 956 [edit on github]
This package lifts a mapping from coefficient rings R to S to a mapping from UnivariatePolynomial(x, R) to UnivariatePolynomial(y, S). Note that the mapping is assumed to send zero to zero, since it will only be applied to the non-zero coefficients of the polynomial.
map(func, poly) creates a new polynomial by applying func to every non-zero coefficient of the polynomial poly.