vpa adding ".0" to the end

Question

Jacob Kelley 2019-11-14

0
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此问题的直接链接

https://ww2.mathworks.cn/matlabcentral/answers/491002-vpa-adding-0-to-the-end

回答： Walter Roberson 2019-11-14

So I am needing to use vpa(#,d) for a very large number on the magnitude of 1x10^(250). I've figured out how to use it but for some reason it adds .0 to the end which I can't have.

example:

n = vpa('3546',32)
disp(n)
output:
3546.0

The reason I can't have the .0 is because I am constructing a sequence that depends on if there are any 0s in the number and the ".0" at the end makes it think it always has a 0 in the number

N = string(n);
strlength(N)
N = convertStringsToChars(N);
for i = 1:strlength(N)
    if N(i) == '0' || N(i) == '1' || N(i) == '5'
        disp('N(i) = 0,1,5')
        skpchk = 'True';
        break;
    end
end

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Answer 1

Walter Roberson 2019-11-14

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此回答的直接链接

https://ww2.mathworks.cn/matlabcentral/answers/491002-vpa-adding-0-to-the-end#answer_401441

https://www.mathworks.com/help/matlab/matlab_prog/searching-and-replacing.html

regexprep can also be used.

I can also offer you code for r2019a and later that converts all floating point software numbers into rationals. In the case of integers with .0 that would construct the integers. However there is the issue that vpa shows you a truncated value that is not necessarily exactly what is stored, so if the numbers do not convert exactly to integers then they might not come out as expected. But the code could easily be adapted to round before converting to rational.