Denominator of a rational expression
This functionality does not run in MATLAB.
denom(f
)
denom(f)
returns the denominator of the expression f
.
denom
regards the input as a rational expression:
nonrational subexpressions such as sin(x)
, x^(1/2)
etc.
are internally replaced by "temporary variables". The
denominator of this rationalized expression is computed, the temporary
variables are finally replaced by the original subexpressions.
We compute the denominators of some expressions:
denom(3/4)
denom(x + 1/(2/3*x 2/x))
denom((cos(x)^2 1)/(cos(x) 1))
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)
This denominator has a common factor with the numerator of r
; normal
enforces
cancellation of common factors:
denom(normal(r))
However, automatic normalization occurs if the input expression is a sum:
denom(r + x/(x + 1) + 1/(x + 1)  1)
delete r:

Arithmetical expression.
f