How to use fprintf function?

Question

Kaylene Widdoes 2015-9-10

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https://ww2.mathworks.cn/matlabcentral/answers/242144-how-to-use-fprintf-function

评论： Walter Roberson 2024-7-30

I have to print the values of f(x) = sin(x^3) at the points x = 5.201, −8323.6, 0.0003 in floating point (f format) with 8 digits after the decimal and in scientific notation (e format) with 10 digits after the decimal.

Any help at all would be appreciated. I have no clue how to do this.

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Answer 1

Star Strider 2015-9-10

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https://ww2.mathworks.cn/matlabcentral/answers/242144-how-to-use-fprintf-function#answer_191908

编辑：Star Strider 2015-9-10

在 MATLAB Online 中打开

The fprintf function optionally requires a ‘fileID’ variable as its first argument, with 1 indicating ‘stdout’, that being the Command Window. Otherwise it will be to the file you want to write to. (I used it in the first fprintf call but not in the second.)

To print the values of ‘x’ and f(x), this works:

x = [5.201, -8323.6, 0.0003];
f = @(x) sin(x.^3);
fprintf(1, 'f(%f) = %.8f\n', [x; f(x)])
fprintf('f(%f) = %.10e\n', [x; f(x)])
f(5.201000) = 0.63076123
f(-8323.600000) = -0.52794696
f(0.000300) = 0.00000000
f(5.201000) = 6.3076122538e-01
f(-8323.600000) = -5.2794696417e-01
f(0.000300) = 2.7000000000e-11

The (\n) is a newline character.

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Kaylene Widdoes 2015-9-10

编辑：Kaylene Widdoes 2015-9-10

This was all I was given. Thanks!

Star Strider 2015-9-10

As always, my pleasure!

I posted a Comment to your Question there, rather than an Answer. I don’t understand the Question well enough to be able to provide an Answer.

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Answer 2

Stephen23 2015-9-10

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此回答的直接链接

https://ww2.mathworks.cn/matlabcentral/answers/242144-how-to-use-fprintf-function#answer_191905

编辑：Stephen23 2015-9-10

在 MATLAB Online 中打开

This should get you started:

>> x = [5.201,-8323.6,0.0003];
>> sprintf(' %.8f',x)
ans =  5.20100000 -8323.60000000 0.00030000
>> sprintf(' %.10e',x)
ans =  5.2010000000e+000 -8.3236000000e+003 3.0000000000e-004

MATLAB has very readable and accessible documentation complete with working examples for you to try out. This is the best place to find out how to do things and how to use functions. You were told what function to use, the next step is to read its documentation and try some of its examples. Then you can see how these can be adapted to your needs, try some small changes... keep on going until you have figured out the problem. Note you should not try to solve any code problem by sitting down writing code! The most important steps are to first understand the problem and then to understand what tools you have to help you, only then comes writing some code...

Here is the fprintf documentation:

http://www.mathworks.com/help/matlab/ref/fprintf.html

I would also highly recommend that you do these tutorials, which are an excellent introduction to MATLAB:

http://www.mathworks.com/help/matlab/getting-started-with-matlab.html

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Kaylene Widdoes 2015-9-10

So the next step would be to write the sin function correct? So wouldn't it be easiest if I defined a function y=(sin(x^3)) and then did the same sprintf code with y(x) rather than x?

Kaylene Widdoes 2015-9-10