gftrunc

Minimize length of polynomial representation

Syntax

c = gftrunc(a)

Description

c = gftrunc(a) truncates a row vector, a, that gives the coefficients of a GF(p) polynomial in order of ascending powers. If a(k) = 0 whenever k > d + 1, the polynomial has degree d. The row vector c omits these high-order zeros and thus has length d + 1.

Examples

Truncate Row-Vector Representation of Galois Field Polynomial

Use gftrunc to truncate the row-vector representation of ${\mathit{x}}^2+{2\mathit{x}}^3+{3\mathit{x}}^4+{4\mathit{x}}^7+{5\mathit{x}}^8$, removing nonsignificant zero-valued elements.

vec = [0 0 1 2 3 0 0 4 5 0 0]

vec = 1×11

     0     0     1     2     3     0     0     4     5     0     0

gfpretty([vec])

 
                         2      3      4      7      8
                        X  + 2 X  + 3 X  + 4 X  + 5 X 

Zeros are removed from the end of the row-vector representation, but not from the beginning or middle of the row vector.

c = gftrunc([0 0 1 2 3 0 0 4 5 0 0])

c = 1×9

     0     0     1     2     3     0     0     4     5

gfpretty(c)

 
                         2      3      4      7      8
                        X  + 2 X  + 3 X  + 4 X  + 5 X 

Version History

Introduced before R2006a