# someTerms -- select some terms of a polynomial

## Synopsis

• Usage:
someTerms(f,i,n)
• Inputs:
• f, , in a polynomial ring
• i, an integer, the starting index
• n, an integer, the number of terms to select
• Outputs:
• , the n terms of the polynomial f starting with the i-th one

## Description

The index i is 0-based, and a negative number refers to location from the end of the polynomial.
 i1 : R = ZZ[a..d]; i2 : f = (a+2*b-3)^2 2 2 o2 = a + 4a*b + 4b - 6a - 12b + 9 o2 : R i3 : someTerms(f,0,1) -- the lead term 2 o3 = a o3 : R i4 : someTerms(f,-1,1) -- the last term o4 = 9 o4 : R i5 : someTerms(f,-2,2) -- the last 2 terms o5 = - 12b + 9 o5 : R
Here is an example where the coefficient ring is also a polynomial ring.
 i6 : S = R[x,y,z]; i7 : f = (x*(a-b)+y^2+a-1)^2 4 2 2 2 2 2 2 o7 = y + (2a - 2b)x*y + (a - 2a*b + b )x + (2a - 2)y + (2a - 2a*b - 2a ------------------------------------------------------------------------ 2 + 2b)x + a - 2a + 1 o7 : S i8 : someTerms(f,-1,1) -- the last term 2 o8 = a - 2a + 1 o8 : S i9 : someTerms(f,-2,2) -- the last 2 terms 2 2 o9 = (2a - 2a*b - 2a + 2b)x + a - 2a + 1 o9 : S