This is documentation for Mathematica 3, which was
based on an earlier version of the Wolfram Language.
 Collect Collect[ expr , x ] collects together terms involving the same powers of objects matching x. Collect[ expr , , , ... ] collects together terms that involve the same powers of objects matching , , ... . Collect[ expr , var , h ] applies h to the expression that forms the coefficient of each term obtained. Collect[ expr , x ] effectively writes expr as a polynomial in x or a fractional power of x. Examples: Collect[x + n x + m, x]; Collect[(1+x+y)^3, x]. Collect[ expr , x , Simplify] can be used to simplify each coefficient separately. See the Mathematica book: Section 1.4.5, Section 3.3.1. See also: Series, CoefficientList, Together, Cases. Further Examples These two inputs collect terms first in the variable x and then in the variable y. In[1]:= Out[1]= In[2]:= Out[2]= This first collects with respect to x, then collects coefficients with respect to y inside of each of the x coefficients. In[3]:= Out[3]= In this example we use Collect to rewrite an expression by pulling out factors common only to certain parts. In[4]:= Out[4]= This example has the usual two arguments. In[5]:= Out[5]= Collect applies an optional third argument to the innermost coefficients of the collected terms. In[6]:= Out[6]= Suppose you want to collect all the products of powers of x and y in a polynomial that involves other variables. One way is to use patterns. In[7]:= Out[7]= Another way is to use MonomialList. In[8]:= Out[8]=