Can I have higher precision while counting with long numbers?

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Jakub Závada 2015-5-1

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https://ww2.mathworks.cn/matlabcentral/answers/214627-can-i-have-higher-precision-while-counting-with-long-numbers

评论： Stephen23 2015-5-2

I wrote function for the number of non-isomorphic graphs on n vertices using Burnside lemma. Function returns correct numbers only for n<14. But for n=14 it returns 29054155657235472 instead of 29054155657235488 and for n>14 there are lots of zeros at the end of the number. I got correct number when I tried to count it for n=14 with the same algorithm in Maple, so algorithm should be right.

And if I can get higher precision, how can I display whole number instead of 3.1426e+19 for n=15 etc?

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Stephen23 2015-5-2

@Jakub Závada: this precision limit exists because MATLAB uses the IEEE 754 floating point classes "double" and "single", which of course have a finite precision. This clearly documented and is expected behavior for any numeric calculation, language or program that ueses these data classes:

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

https://en.wikipedia.org/wiki/Double-precision_floating-point_format

Numeric computation is not the same thing as symbolic calculation!

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