simple inequality check fails - why?

8 views (last 30 days)
L. C.
L. C. on 27 Jun 2012
Answered: timo on 2 Jan 2015
Hi,
I have the simple inequality check for testing purposes in MuPad:
assume(0<x<1)
assumeAlso(0<y<1)
assumeAlso(A>0)
is(1/(1-x) >=1/(1-x*y))
is(A/(1-x) >=A/(1-x*y))
The first check correctly evaluates to TRUE, but the second returns UNKNOWN, however it is obviously true. Am I doing something wrong, or I have reached the limitation of the tool?

Answers (3)

Tom
Tom on 27 Jun 2012
You have to split up the comparisons: e.g.:
x > 0 & x < 1
  1 Comment
L. C.
L. C. on 28 Jun 2012
Thanks. I tried and nothing has changed. Other ideas? I also tried to introduce an upper bound on A as well to avoid possible mess with infinity, but the result is just the same.

Sign in to comment.


Radu Trimbitas
Radu Trimbitas on 10 Sep 2014
Your code works works correctly in MATLAB 2014a.

timo
timo on 2 Jan 2015
For me evaluates to:
TRUE TRUE
in mupad for Symbolic Math Toolbox Version 6.1 (R2014b)

Community Treasure Hunt

Find the treasures in MATLAB Central and discover how the community can help you!

Start Hunting!