Bug with normf and renorm()

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Vito Spadevecchio

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Aug 8, 2015, 9:40:27 PM8/8/15
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I've noticed that the way in which data is normalized, and subsequently unnormalized, is flawed in neurolab (but it might just be a np problem?) 

For example, I have the following column as my target column: 

-7.933

-9.633

-7.853

-9.113

-8.263

-9.023

-10.333

-7.853

-9.343

-9.153


After the data is initialized (using nl.tool.Norm()), the following is the output 

0.97899649941656963

0.89148191365227547

0.87281213535589275

1

0.51108518086347732

0.33255542590431747

0

0.93932230102442871

1

0


As it should be first apparent, this normalization isn't correct (e.g. both -9.343 and -9.113 are normalizing to '1', when neither is the maximum value"). 

If you then renormalize the same column, you get the following output: 

-7.890386231038506

-8.0461621936989491

-8.0793943990665102

-7.8529999999999998

-8.7232683780630094

-9.0410513418903147

-9.6329999999999991

-7.9610063041765162

-7.8529999999999998

-9.6329999999999991


While close, these values *do not* match the values before being normalized and then de-normalized (they should be exactly the same). These small errors are causing me a major headache, as errors are within the range of accuracy that I'm looking for. 
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