通过sprintf()和fprintf()的Matlab ShortEng数字格式? [英] Matlab ShortEng number format via sprintf() and fprintf()?

问题描述

我喜欢在交互式命令窗口中使用MATLAB的shortEng表示法:

I like using MATLAB's shortEng notation in the interactive Command Window:

>> a = 123e-12;
>> disp(a);

   1.2300e-10       % Scientific notation. Urgh!

>> format shortEng;
>> disp(a);

   123.0000e-012    % Engineering notation! :-D

但是我想使用fprintf:

But I want to use fprintf:

>> format shortEng;
>> fprintf('%0.3e', a); 
1.2300e-10          % Scientific. Urgh!

如何使用MATLAB 格式运算符?

How do I print values with fprintf or sprintf with Engineering formatting using the MATLAB Format Operators?

我知道我可以编写自己的函数以将值格式化为字符串，但是我正在寻找已经内置在MATLAB中的东西.

I know I could write my own function to format the values into strings, but I'm looking for something already built into MATLAB.

注意:工程"表示法与科学"表示法的不同之处在于，指数始终是3的倍数.

NOTE: "Engineering" notation differs from "Scientific" in that the exponent is always a multiple of 3.

>> fprintf('%0.3e', a);    % This is Scientific notation.
1.230000e-10

推荐答案

无法直接将fprintf格式说明符用于所需的格式.一种解决方法是将disp的输出用作要打印的字符串.但是disp不返回字符串，而是直接写入标准输出.那么，该怎么做呢?

There is no way to use directly fprintf format specifier for the format you require. A way around is to use the output of disp as a string to be printed. But disp doesn't return a string, it writes directly to the standard output. So, how to do this?

在这里evalc(带有捕获输出的信息)可以进行救援:

Here's where evalc (eval with capture of output) comes to the rescue:

%// Create helper function
sdisp = @(x) strtrim(evalc(sprintf('disp(%g)', x)));

%// Test helper function
format ShortEng;
a = 123e-12;
fprintf(1, 'Test: %s', sdisp(a));

当然，这是一种解决方法，由于辅助功能的未经测试的输入，它可能会以多种方式适得其反.但这说明了这一点，并且是被指责的eval函数族实际上不可替代的罕见情况之一.

This is a workaround, of course, and can backfire in multiple ways because of the untested inputs of the helper functions. But it illustrates a point, and is one of the rare occasions where the reviled eval function family is actually irreplaceable.

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