the isnumeric function and the NaN

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Snoopy 2018-9-7

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编辑： Snoopy 2018-9-7

I have a matrix array (A) that includes three column arrays. All columns contain integers except that one of the columns also include NaNs. When I type isnumeric(A), the output is a logical value 1. Apparently NaN is recognised as a numeric entry as otherwise MATLAB would return a logical value of 0. How is a NaN recognised exactly?

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Stephen23 2018-9-7

编辑：Stephen23 2018-9-7

@Snoopy: The behavior of NaN's within MATLAB operations is explained here:

https://www.mathworks.com/help/matlab/matlab_prog/infinity-and-nan.html

NaN's are just a particular bit pattern that is assigned to have the value Not-a-Number. To know more about the classes that support NaN's, you need to read about IEEE 754 standard (the well-supported 1985 version), which defines the floating point numbers that MATLAB uses:

https://www.mathworks.com/help/matlab/matlab_prog/floating-point-numbers.html

This also explains how the numbers are stored, including the "special" values like Inf and NaN:

https://en.wikipedia.org/wiki/IEEE_754-1985

Snoopy 2018-9-7

编辑：Snoopy 2018-9-7

This is it. Thanks for the effort and time put into the answer. I wanted to accept this as answer but it seems comment cannot be marked as such. Sorry for this.

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