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denom -- the denominator of a rational expression

Introduction

denom(f) returns the denominator of the expression f.

Call(s)

denom(f)

Parameters

f - an arithmetical expression

Returns

an arithmetical expression.

Overloadable:

f

Related Functions

gcd, factor, normal, numer

Details

Example 1

We compute the denominators of some expressions:

>> denom(-3/4)
                                     4
>> denom(x + 1/(2/3*x -2/x))
                                    2
                                 2 x  - 6
>> denom((cos(x)^2 -1)/(cos(x) -1))
                                cos(x) - 1

Example 2

denom performs no cancellations if the rational expression is of the form ``numerator/denominator'':

>> r := (x^2 - 1)/(x^3 - x^2 + x - 1): denom(r)
                                   2    3
                              x - x  + x  - 1

This denominator has a common factor with the numerator of r; normal enforces cancellation of common factors:

>> denom(normal(r))
                                   2
                                  x  + 1

However, automatic normalization occurs if the input expression is a sum:

>> denom(r + x/(x + 1) + 1/(x + 1) - 1)
                                   2
                                  x  + 1
>> delete r:

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