MATLAB: The mantissa of a floating point number??

floating point numbermantissa

What is the mantissa of a floating point number? How would you find it?

Best Answer

It's the fractional part of a real number.

http://mathworld.wolfram.com/Mantissa.html

In MATLAB, you can calculate the mantissa of x as

>> x - floor(x)

There are lots of places to read about floating point numbers and their representation. Here's one:

http://www.mathworks.com/company/newsletters/news_notes/pdf/Fall96Cleve.pdf

Please see James Tursa's answer for a cautionary note about the two different definitions of mantissa! Since you asked about binary form, I expect you mean the one from the Cleve Moler article, not the Mathworld article definition (or the formula I gave).

Related Solutions

MATLAB: Expressing floating point numbers in IEEE standard

Did you look at my answer to your other question yet? Here:

http://www.mathworks.com/matlabcentral/answers/67491-the-mantissa-of-a-floating-point-number

The document I point you to in that answer talks about that exact topic. Here's the link again, for your convenience:

http://www.mathworks.com/company/newsletters/news_notes/pdf/Fall96Cleve.pdf

MATLAB: Efficient way to get MSB position of a double variable

My guess is you're trying to get the index of the most significant bit of an integer, not a floating point double (where a number is divided in two parts, mantissa and exponent, so not sure what you'd call the msb).

To get that value:

xMsb = nextpow2(x);

is simpler but probably not as fast as your algorithm. You can look at the code for nextpow2, it is implemented as m file.

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Related Solutions

MATLAB: Expressing floating point numbers in IEEE standard

MATLAB: Efficient way to get MSB position of a double variable

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