How to prevent reduction of a fraction into lowest terms?

16

3

I have a question about the concept of simplification. I want to explain it with an example. When I write the fraction $4/8$ in Mathematica, the output is

1/2.

How can I return this expression as $4/8$? How can I prevent simplifying rational numbers in lowest terms?

MATIRMAK

Posted 2014-12-30T19:03:34.473

Reputation: 719

Can't u use "4/8"? ;) – Elf – 2014-12-30T19:13:11.147

2HoldForm[4/8], and many Examples, if you use the search function on this page. – None – 2014-12-30T19:14:00.803

4... or Defer[4/8]. – kglr – 2014-12-30T19:14:54.907

3... or check out Inactivate – Jacob Akkerboom – 2014-12-30T19:18:25.940

Thank you for your comments. Since i am a new user of mathematica, i dont know the functions very well. the functions Defer and HoldForm is ok for me. Best regards... – MATIRMAK – 2014-12-30T19:19:15.140

I'm sure this is a duplicate but I can't find the previous question. – Simon Woods – 2014-12-30T20:13:31.203

I just wonder why you'd want to do that – Dr. belisarius – 2014-12-30T20:26:10.160

i am interested in farey sequences. So, i should have the list of farey sequence exactly. When i try to obtain it by mathematica, i could not get the list regularly since mathematica simplifies the fractions. Therefore, i need to unsimplification version of a fraction. – MATIRMAK – 2014-12-30T20:34:18.350

possible duplicate of TeXForm without simplification

– Yves Klett – 2014-12-31T11:23:00.620

Answers

29

You can use the internal function Internal`RationalNoReduce

Internal`RationalNoReduce[4, 8]

enter image description here

Internal`RationalNoReduce[4, 8]^2 + 5

enter image description here

Chip Hurst

Posted 2014-12-30T19:03:34.473

Reputation: 29 735

5Never seen that before. +1 – Mr.Wizard – 2015-01-11T09:49:17.677