coeffs(P) returns the coefficients of the polynomial P with respect to all the indeterminates of P.

coeffs(P,x) returns the coefficients of the polynomial P with respect to x.

[c, t] = coeffs(P,x) also returns an array of the terms of P.  The terms of P line up such that add(i,i=zip(`*`,a,b)); gives back the original polynomial, P.

$\mathrm{with}\left(\mathrm{MTM}\right)\:$

$t≔2+{\left(3+4\log \left(x\right)\right)}^2-5\log \left(x\right)$

$t≔2+{\left(3+4\ln \left(x\right)\right)}^2-5\ln \left(x\right)$

$\mathrm{coeffs}\left(\mathrm{expand}\left(t\right)\right)$

$\left[\begin{array}{ccc}11& 16& 19\end{array}\right]$

$y≔a+b\sin \left(x\right)+c\sin \left(2x\right)$

$y≔a+b\sin \left(x\right)+c\sin \left(2x\right)$

$\mathrm{coeffs}\left(y\,\sin \left(x\right)\right)$

$\left[\begin{array}{cc}a+c\sin \left(2x\right)& b\end{array}\right]$

$\mathrm{coeffs}\left(\mathrm{expand}\left(y\right)\,\sin \left(x\right)\right)$

$\left[\begin{array}{cc}a& b+2c\cos \left(x\right)\end{array}\right]$

$z≔3x^2{u}^2+5x{u}^3$

$z≔5x{u}^3+3x^2{u}^2$

$\mathrm{coeffs}\left(z\right)$

$\left[\begin{array}{cc}5& 3\end{array}\right]$

$\mathrm{coeffs}\left(z\,x\right)$

$\left[\begin{array}{cc}3u^2& 5u^3\end{array}\right]$

$\left[c\,t\right]$

$\left[c\,2+{\left(3+4\ln \left(x\right)\right)}^2-5\ln \left(x\right)\right]$