How to change e format?

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hyein Sim 2021-3-19

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此问题的直接链接

https://ww2.mathworks.cn/matlabcentral/answers/777472-how-to-change-e-format

评论： hyein Sim 2021-3-21

采纳的回答： Walter Roberson

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I want to change the number's format.

I written

x=[0.00005; 0.0002; 1.00; 0.0015; 0.02; 0.01;];
txt=sprintf('%.e %.4f %.2f %.4f %.2f %.2f',x);

and the result is txt

5.e-05 0.0002 1.00 0.0015 0.02 0.01

But I want to change

x=[0.00005; 0.0002; 1.00; 0.0015; 0.02; 0.01;];

x=[5E-005; 0.0002; 1.00; 0.0015; 0.02; 0.01;];

What can I do for this?

Plz help me... ;(

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Rik 2021-3-19

So you just want to format the exponent with 3 digits instead of 2? (And use '%.4f' for values larger than 5e-5)

hyein Sim 2021-3-21

@Rik Yes!! :)

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采纳的回答

Walter Roberson 2021-3-19

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https://ww2.mathworks.cn/matlabcentral/answers/777472-how-to-change-e-format#answer_653022

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Please check the output for pi/1000 . Is the rule intended to be "up to 9 decimal places" like it is for 0.000314159, which would give 0.003141592 if you used truncation and 0.003141593 if you used rounding. But perhaps the rule is non-zero plus up to 5 further (so up to 6 decimal places counting from the first non-zero), in which case pi/1000 would give 0.00314159 through rounding or truncation. But if the input value happened to be 0.003141596 and the rule is non-zero+5, then is truncation to 0.00314159 okay, or would you require rounding to 0.00314160 ? And in that case where the trailing digit is not "naturally" 0 but rounded to it, do you want to preserve the trailing 0 or get rid of it, to 0.0031416 ?

Note: I preserved the trailing semi-colon before the ] that you had in your output, in case it was meaningful.

Note: I did not attempt to detect row-vectors and use commas for those, and I did not attempt to deal with 2D arrays.

x = [0.00005; 0.0002; 1.00; 0.0015; 0.02; 0.01; pi/1000; pi/10000];
txt = format_vector(x);
disp(txt)
[5E-005; 0.0002; 1.00; 0.0015; 0.02; 0.01; 0.003141593; 0.000314159;]
function txt = format_vector(vec)
  txt = ['[', strjoin(arrayfun(@format_number, vec, 'uniform', 0), ' '), ']'];
end
function str = format_number(num)
    %format of each number includes a trailing semi-colon
    if abs(num) >= 1e-4
        str = sprintf('%.9f;', num);
        %Rule: 1 exactly becomes '1.00' not '1.' so preserve at least 2
        %decimal places
        %Rule: but otherwise trim trailing 0
        str = regexprep(str, '0{1,7};$', ';');
    else
        %Rule: exponent must have three digits
        %Rule: trailing 0 after period must be removed
        %Rule: if all digits after period are 0, remove period too
        %Rule: exponent character must be 'E' not 'e'
        str = sprintf('%.5E;', num);
        str = regexprep(str, {'0+E', '\.E'}, {'E', 'E'});
        str = regexprep(str, {'(E[-+])(\d);$', '(E[-+])(\d\d);$'},{'$100$2;', '$10$2;'});
    end
end

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hyein Sim 2021-3-21

Thank you for kind responses 👍 I will try this and write the results.

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