Numerator

Numerator

Numerator[ f ] returns the numerator of a fraction.

Usages

Numerator[ f ]

Numerator[ f ] returns the numerator of the fraction f, exactly as it is written. f can be a fraction of numbers, a mixed number or a division of expressions. A mixed number is first written as one fraction.

Example in out
A fraction. Numerator[ 2/3 ] 2
The fraction is not simplified first. x := 2/6
r := Numerator[x]		 r = 2
A negative fraction. Numerator[ -3/4 ] -3
The mixed number 2 3/4 = 11/4. Numerator[ Rational[1,2,3,4] ] 11
The mixed number -2 3/4 = -11/4. Numerator[ Rational[-1,2,3,4] ] -11
A division of expressions. Numerator[ (x+1)/(x-1) ] x+1

Numerator[ list ]

If the argument is a list, the numerator of each element is returned.

Example in out
The numerators of two fractions. Numerator[ {1/2, 3/4} ] {1, 3}
Details
  • Not a fraction: anything that is not written as a fraction or division is returned unchanged: Numerator[ 5 ] gives 5, Numerator[ 0.5 ] gives 0.5 and Numerator[ x^(-1) ] gives x^(-1). Use DecimalToFraction to convert a decimal number first.

See also: Denominator, DecimalToFraction