Why does not coefficients vector include zero?

Hi,

In this code, cf should be [3 2 0], but the output is different. What is the reason of this?

Thanks,

clear all
clc
syms x y z
cf = fliplr(coeffs(x*3 + 2*y, [x y z],'All'))

>>cf =
[3, 0]
[0, 2]

Answer 1

[Bjorn Gustavsson]

When I change the polynomial to:

cf = fliplr(coeffs(x*3 + 2*z, [x y z],'All'))

I get a 3-D array for the coefficients, as expected. What you see might be the effect of matlabs reduction of the trailing dimensions. Compare for example with:

size(randn(12,23,1))

I don't know how to solve this for you, unfortunately. Maybe you can add a term with high enough degree in your last variable to avoid that type of reduction and then crop the output for your future manipulations - this seems like a very messy idea.

HTH

[Volkan Yangin]

Hi Bjorn, thanks a lot for your suggestion.