numerical integration dimension error

2011 3 2
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ok now Im getting another type of error
X = 0:1:100; Y = X.^(-1/2)*exp(-0.5*(0.00009996^2/X+34.3713^2*X)); Z =trapz(X,Y)
??? Error using ==> mldivide
Matrix dimensions must agree.
Whats wrong here? and how can I numerically integrate Y?

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Matt Fig
Matt Fig 2011-3-2

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You need a dot before every ^, * and / when working with vectors.
Y = X.^(-1/2).*exp(-0.5*(0.00009996^2./X+34.3713^2*X));

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john birt
john birt 2011-3-2
what do you mean?
X = 0:1:100; Y = X.^(-1/2).*exp(-0.5.*(0.00009996.^2./X+34.3713.^2.*X)); Z = trapz(X,Y)
is that correct as it produces Z = NAN which I was not expecting?
Matt Fig
Matt Fig 2011-3-2
You may not be expecting NAN, but that is how to make Y from X. Look at the exponent, it has values from -590 to -Inf. What do you think e^-590 is? ZERO (for all intents and purposes).
john birt
john birt 2011-3-2
Thanks for your wisdom, I can get an answer if I change it to something like
X = 0.001:0.001:0.003; Y = X.^(-1/2).*exp(-0.5*(0.00009996^2./X+34.3713^2*X)); Z = trapz(X,Y)
Z = 0.0172
thanks again for your comments (dumb matlab coders like me need help!)

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