# AmplNLWriter, NLexpression, can't evaluate pow('(0,0.45),

**URL:** <https://discourse.julialang.org/t/amplnlwriter-nlexpression-cant-evaluate-pow-0-0-45/26006>\
**Category:** Optimization (Mathematical)\
**Created:** [July 4, 2019, 9:13am UTC](https://discourse.julialang.org/t/amplnlwriter-nlexpression-cant-evaluate-pow-0-0-45/26006 "2019-07-04T09:13:41Z")\
**Posts on this page:** 1\
**Showing post:** 2

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**Author:** ![odow](https://sea2.discourse-cdn.com/julialang/user_avatar/discourse.julialang.org/odow/32/28685_2.png) [@odow](https://discourse.julialang.org/u/odow)\
**Post date:** [July 5, 2019, 1:33pm UTC](https://discourse.julialang.org/t/amplnlwriter-nlexpression-cant-evaluate-pow-0-0-45/26006/2 "2019-07-05T13:33:48Z")

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Please read: [Please read: make it easier to help you](https://discourse.julialang.org/t/psa-make-it-easier-to-help-you/14757).

Particularly about formatting your code with triple-backticks, and providing a minimum working example (e.g., what is `QP`?). Also provide the full error.

The likely culprit is that `x[i,j] * QP[i] / 3600 / 24` is too small for Couenne’s numerical precision.

Does the error go away if you make the lower bounds a lot larger (e.g., `>= 0.1`)?

You could also think about rescaling the problem. For example, you could multiple the objective by 10\_000 to get some nicer numbers.

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_[View the full topic](https://discourse.julialang.org/t/amplnlwriter-nlexpression-cant-evaluate-pow-0-0-45/26006)._