Error in using Integration, How to fix it ?
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I am trying to plot a function with integration in it, and it always gives me an error in using the integral, I tried using function handle for the first argument (according to the error) , but the error remaind.
t = 0:0.02:20;
y = 0:1000;
x = @(t,y) (y/((4*t*0.02/1000)^0.5));
fun = @(x)(exp(-x.^2));
erf = (2/pi^(0.5)) *integral(fun,0,x); % the error is in this line
erfc= 1 - erf;
VProfile= 10*erfc;
plot(t,VProfile)
title('Velocity Profile')
xlabel('time (sec)')
ylabel('Velocity (cm/sec)')
so what did I do wrong? and how can I fix it ? and if the code has another error I didnt notice, please point it out.
thank you.
采纳的回答
Alan Stevens
2021-1-12
编辑：Alan Stevens
2021-1-12
Since x has t in the denominator. t=0 will cause problems, so start at t = 0.02 instead, perhaps! This would require a change in y to get the same number of elements as t.
You don't need x as a function. Replace with
x = y./((4*t*0.02/1000).^0.5);
then calculate your error function in a loop:
for i = 1:numel(t)
erf(i) = (2/pi^(0.5))*integral(fun,0,x(i));
end
Best not to use erf and erfc as they are functions already built-in to MATLAB. Better as, say, erF and erFc.
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