MATLAB: How to multiply function handles

functionhandlemultiply

Hello,
I would like to calculate and to plot the following equation:
f(t,x) = (beta_hat*s(t,x)*[I(t,x)]^(beta_hat-1))*exp(-[I(t,x)]^beta_hat)
where:
      s(t,x): step-function(330 for x=[0;2000])
                           (350 for x=[2000;3000])
                           (390 for x=[3000;4000])
     I(t,x): Integral(exp(-B_hat/x(u))/C_hat)) from x=0 to t
     beta_hat, C_hat and B_hat are known parameters
My MATLAB-script looks like that:
beta_hat = 4.2915822 
B_hat = 1861.6186657 
C_hat = 58.9848692  
%%Step-function x(t)
syms t 
y(t) = (exp(-B_hat/((heaviside(t)-heaviside(t-2000))*(330)+(heaviside(t-2000)-heaviside(t-3000))*(350)+...
       (heaviside(t-3000)-heaviside(t-4000))*(390))))/C_hat;  
fnum=matlabFunction(y);
Inum=@(x)integral(fnum,0,x);
f = @(x)(beta_hat*fnum(x).*Inum(x).^(beta_hat-1)).*exp(-(Inum(x).^beta_hat))
ezplot(f,[0,14000])
But if I plot my function f the figure isn´t right. There should be a smooth curve, similar to the bell-shaped curve.
Does anybody recognize my fault?

Best Answer

What value are you assuming that heaviside(0) has?
As you are working with the Symbolic toolbox anyhow, have you considered doing a symbolic integration with int() instead of changing to a numeric function and using integral() ?
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