Plotting an integral function

Question

Kristine 2022-8-3

0
链接

此问题的直接链接

https://ww2.mathworks.cn/matlabcentral/answers/1772955-plotting-an-integral-function

编辑： Torsten 2022-8-3

采纳的回答： Torsten

在 MATLAB Online 中打开

I am trying to plot the followng equation. I am solving for stress.

My professor has told us that h' will be negative in the first and positive in the second. I used the following code, but my plot just shows a straight line. I think I should end up with a curve.

L=1.5;
h=.2;
s=.75*L;
tbar=1;
y=0;
for xbar=-1.5:.1:1.5
    if xbar>-L & s>xbar
        hprime=0.75; 
    else
        hprime=-0.75;
    end
    fun= @(xbar) ((2*hprime)*((xbar-tbar)^3))/(((xbar-tbar)^2+y^2)^2); 
    Sxx1=integral(fun,-L,-s, 'ArrayValued',1);
    Sxx2=integral(fun,s,L, 'ArrayValued',1);
    Sxx=(((L-s)/h)*(Sxx1+Sxx2));
    figure(1)
    plot(Sxx,xbar,'.')
    hold on
    grid
    title('Sxx vs xbar')
end

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Answer 1

Torsten 2022-8-3

1
链接

此回答的直接链接

https://ww2.mathworks.cn/matlabcentral/answers/1772955-plotting-an-integral-function#answer_1020105

在 MATLAB Online 中打开

L=1.5;

h=.2;

s=.75*L;

tbar=1;

y=0;

icount = 0;

for xbar=-1.5:.1:1.5

icount = icount + 1;

if xbar>-L & s>xbar

hprime=0.75;

else

hprime=-0.75;

end

fun= @(tbar) ((2*hprime)*((xbar-tbar)^3))/(((xbar-tbar)^2+y^2)^2);

Sxx1=integral(fun,-L,-s, 'ArrayValued',1);

Sxx2=integral(fun,s,L, 'ArrayValued',1);

Sxx(icount)=(((L-s)/h)*(Sxx1+Sxx2));

%figure(1)

%plot(Sxx,xbar,'.')

%hold on

%grid

%title('Sxx vs xbar')

end

Warning: Minimum step size reached near x = -1.5. There may be a singularity, or the tolerances may be too tight for this problem.

Warning: Reached the limit on the maximum number of intervals in use. Approximate bound on error is 7.9e+00. The integral may not exist, or it may be difficult to approximate numerically to the requested accuracy.

Warning: Reached the limit on the maximum number of intervals in use. Approximate bound on error is 5.3e+00. The integral may not exist, or it may be difficult to approximate numerically to the requested accuracy.

Warning: Reached the limit on the maximum number of intervals in use. Approximate bound on error is 1.5e+01. The integral may not exist, or it may be difficult to approximate numerically to the requested accuracy.

Warning: Reached the limit on the maximum number of intervals in use. Approximate bound on error is 5.3e+00. The integral may not exist, or it may be difficult to approximate numerically to the requested accuracy.

Warning: Reached the limit on the maximum number of intervals in use. Approximate bound on error is 8.0e+00. The integral may not exist, or it may be difficult to approximate numerically to the requested accuracy.

Warning: Minimum step size reached near x = 1.5. There may be a singularity, or the tolerances may be too tight for this problem.

plot(-1.5:0.1:1.5,Sxx)