using for loop plotting problem help me
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function homework
f= @(x) 3*x^5+7*sind(x)^2;
fd= @(x) 15*x^4+7*sind(2*x)^2+3*x^5+7*sind(x)^2;
a=-1;
b=3;
n=5;
e=1.1*10^3;
s=(fd(a)+fd(b));
for i=1:1:n-1
h=(b-a)/i;
s=s+2*fd(i);
I=(h/2).*s
error=I-e
end
end
the problem is ı have values but try everything for plotting but see nothing even there is no line or spline .
3 个评论
Cris LaPierre
2021-1-12
Why do you expect to see a plot? You haven't included any plotting commands. See Ch 9 of MATLAB Onramp for help with plotting.
ataberk kaplica
2021-1-12
Rik
2021-1-12
This time I edited your question for you (also removing most blank lines). Next time, please use the tools explained on this page to make your question more readable.
I don't understand your comment. Your function does not contain any plotting functions, and at the end of a function all variables that aren't output variables will be wiped.
Also, you overwrite the contents of you variables every iteration of your loop. You may also want to look at the Onramp part concerning loops and indexing.
采纳的回答
Mathieu NOE
2021-1-12
hello
I assumed that you wanted to plot I and error , but you forgot to index thos variables
see below :
f= @(x) 3*x^5+7*sind(x)^2;
fd= @(x) 15*x^4+7*sind(2*x)^2+3*x^5+7*sind(x)^2;
a=-1;
b=3;
n=5;
e=1.1*10^3;
s=(fd(a)+fd(b));
for i=1:1:n-1
h=(b-a)/i;
s=s+2*fd(i);
I(i)=(h/2).*s;
error(i)=I(i)-e;
end
figure(1),plot(1:n-1,I,'b')
figure(2),plot(1:n-1,error,'r')
6 个评论
ataberk kaplica
2021-1-12
ataberk kaplica
2021-1-12
Mathieu NOE
2021-1-12
ok
so also h needs to be indexed in your loop
final code is :
f= @(x) 3*x^5+7*sind(x)^2;
fd= @(x) 15*x^4+7*sind(2*x)^2+3*x^5+7*sind(x)^2;
a=-1;
b=3;
n=5;
e=1.1*10^3;
s=(fd(a)+fd(b));
for i=1:1:n-1
h(i)=(b-a)/i;
s=s+2*fd(i);
I(i)=(h(i)/2).*s;
error(i)=I(i)-e;
end
figure(1),plot(h,error,'r')
ataberk kaplica
2021-1-12
Mathieu NOE
2021-1-12
you're welcome !
Rik
2021-1-12
Just a note: you should avoid using function names as variable names. It is very common to want to use the error function, so shadowing it is a bad habit (similar to max, mean, and sum).
更多回答（1 个）
David Hill
2021-1-12
What are you trying to plot?
f= @(x) 3*x.^5+7*sin(x).^2;%I doubt you want sind
fd= @(x) 15*x.^4+7*sin(2*x).^2+3*x.^5+7*sin(x).^2;
x=-1:.01:3;
plot(x,f(x),x,fd(x));
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