How do I plot the output of a for loop?

Question

JJH 2018-11-3

0
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此问题的直接链接

https://ww2.mathworks.cn/matlabcentral/answers/427765-how-do-i-plot-the-output-of-a-for-loop

I have a code that computes the difference between the exponential function in matlab and an approximation of it using the Taylor expansion. I have also computed how many terms of the Taylor expansion are needed to make the expansion a particular degree of accuracy. However, I also want to plot the error at each point as a function of how many terms have been used in the Taylor expansion. I can get my code to give a plot but the plot is incorrect and I'm unsure what's going wrong. The codes I have written so far are

    x=2;
expapprox=0;
prompt = 'How many terms in the expansion?'
for i=0:input(prompt)
    expapprox=expapprox+x^i/factorial(i);
end
error=abs(expapprox-exp(x))
clear;
n=0;
x=2;
expapprox=0;
while abs(expapprox-exp(x))>=0.001
    expapprox=expapprox+x^n/factorial(n);
    n=n+1;
end
n
clear;
x=2;
expapprox=0;
expapproxarray=zeros(1,12);
for j=1:length(expapproxarray)
    for i=0:12
        expapprox=expapprox+x^i/factorial(i);
        error=abs(expapprox-exp(x))
        expapproxarray(j)=error
    end    
end
plot(expapproxarray)