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From |
Conor Hughes <cbhughes@uchicago.edu> |

To |
statalist@hsphsun2.harvard.edu |

Subject |
Re: st: Stata cannot do math? |

Date |
Wed, 18 May 2011 19:20:57 -0500 |

Hi, Stata can certainly do math, just not quite the same math you're used to. This is an issue of floating point arithmetic. For example, replace count a == 100.1 in your code with count a == float(100.1) Click through the FAQ a bit, maybe starting here http://www.stata.com/support/faqs/data/float.html, as well as any introductory numerical analysis textbook to get a better idea of how computer arithmetic works. - Conor On Wed, May 18, 2011 at 6:44 PM, Yu Xue <snowrain@gmail.com> wrote: > > Hi All, > > This may be a stupid question. Here are the command and Stata output: > > .set obs 50 > .gen a=100.1 > .count if a==100.1 > 0 > .tab a > 100.1 > .sum a > variable obs mean s.d. min max > a 50 100.1 0 100.1 100.1 > .gen b=a-100 > .tab b > 0.0999985 > > So, Stata shows that a is equal to 100.1, but actually, it is equal to > 100.0999985.... > > Can anyone explain to me what this is? Do I have to set precision when > I do math in Stata? How to set precision? > Thanks! > > Yu > * > * For searches and help try: > * http://www.stata.com/help.cgi?search > * http://www.stata.com/support/statalist/faq > * http://www.ats.ucla.edu/stat/stata/ * * For searches and help try: * http://www.stata.com/help.cgi?search * http://www.stata.com/support/statalist/faq * http://www.ats.ucla.edu/stat/stata/

**Follow-Ups**:**Re: st: Stata cannot do math?***From:*Ronan Conroy <rconroy@rcsi.ie>

**Re: st: Stata cannot do math?***From:*Yu Xue <snowrain@gmail.com>

**References**:**st: Stata cannot do math?***From:*Yu Xue <snowrain@gmail.com>

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