CoefficientList

CoefficientList[poly,var] gives a list of coefficients of powers of var in poly, starting with power 0. 

CoefficientList[poly,{var1,var2,…}] gives an array of coefficients of the vari. 

CoefficientList[poly,{var1,var2,…},{dim1,dim2,…}] gives an array of dimensions {dim1,dim2,…}, truncating or padding with zeros as needed.

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