fprintf to plot error

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Edinson Manga 2020-5-28

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https://ww2.mathworks.cn/matlabcentral/answers/536123-fprintf-to-plot-error

评论： Walter Roberson 2020-5-28

I need convert fprintf of y0 to vector for plot (x,y0)

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Geoff Hayes 2020-5-28

Edinson - what exactly is your question? Is there a problem with the fprintf? Please claridy. Also, please don't post a screen shot of your code...attach the code or copy and paste it into your question.

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Answer 1

Edinson Manga 2020-5-28

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clear all close all clc

f=@(x,y)2*(2*sin(x)+cos(x))-5*sin(x); %Write your f(x,y) function, where dy/dx=f(x,y), x(x0)=y0. x0=0; %example x0=0 y0=1; %example y0=0.5 xn=4;% where we need to find the value of y %example x=2 h=0.05; %example h=0.2 %Formula: k1=h*f(x0,y0); k2=h*f(x0+h,y0+k1); y1=y0+(k1+k2)/2; fprintf('\n x y '); while x0<=xn i=0; fprintf('\n%4.3f %4.3f ',x0,y0); %values of x and y k1=h*f(x0,y0); x1=x0+h; k2=h*f(x1,y0+k1); y1=y0+(k1+k2)/2 ; x0=x1 y0=y1; i=i+1; x=0:0.05:4

end

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Edinson Manga 2020-5-28

the problem is that I have no idea how I can pass the different y0 that fprintf throws a cumulative vector in order to graph

Walter Roberson 2020-5-28

That should have been posted as a Comment to your Question.

When you edit it in up there, first press the ">" button in the CODE section of the editor toolbar, and then paste your nicely indented code into the area that creates, so that it gets post as formatted code.

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Answer 2

Walter Roberson 2020-5-28

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此回答的直接链接

https://ww2.mathworks.cn/matlabcentral/answers/536123-fprintf-to-plot-error#answer_440923

See https://www.mathworks.com/matlabcentral/answers/534868-make-matrix-with-loop#answer_439778 for a general code outline that you should probably use.

Question: why do you change x each iteration of the loop? You do not use x in the loop.

Why are you initializing i in the loop and then incrementing it (so each loop you set it to zero and then set it to one.) You are not using i anywhere. If you want to know how many iterations it takes you should not be setting i to 0 each time.