Recent content by jaejoon89

How do you use a TI-89 to get phi(z) when you do a confidence interval, i.e. phi(z) = 1/2 (1 + erf(z / sqrt(2))) The Normal CDF function has lower and upper values so I don't see how I can do it, and erf(z) doesn't do anything when I enter it so it must not be built in. Integrating the error...

Using MATLAB, how do you evaluate a function at integer values, say 1 to 1000, of x and y? For simplicity, let's say the function is z = x + y.

In class, my teacher gave the following equations as examples of linear and nonlinear ODE. In the first equation, there are x's in front of some of the y's yet it is linear. In the second equation, there is an x in front of y^2 yet it is nonlinear - why? Also, why is the final equation...

There's a technique for diagonalizing the matrices of large systems in chemistry in order to simplify the matrix and be able to figure out the eigenvalues, which have physical meaning. I don't understand how it works. How can it work without having an eigenbasis...

How do you diagonalize a matrix without first determining its eigenvalues then eigenvectors? All of the examples I've seen first find the eigenvalues and eigenvectors, then diagonalize it. That seems to obscure why you'd want to diagonalize it in the first place - to easily compute the eigenvalues!

When I solve the way my teacher did by labeling each atom as the i, j values, I get a 2x2 matrix that I solve to obtain w = sqrt(C_HO) That means w = sqrt(C ' _HO / sqrt(M_O M_H)) But w = sqrt(k / mew) and the above doesn't simplify to that - what am I missing?

Can Wilson's GF (FG) Matrix Method be applied to linear molecules as well as nonlinear? For example, can it be applied to a linear chain of hydrocarbons? What are some of the restrictions?

I'm referring to the classical case. In the stuff I've read about it, it's called the "mass-weighted Hessian matrix," ||Cij|| in pg. 15 of Feynmann's book (link to view it is in my original post). In any case, I don't know how to find the values for it for my particular example (hydroxyl...

Thanks, I guess what is confusing is Feynman uses i and j for both the cartesian and mass-weighted coordinate cases. One last question: how are the explicit values in the Hessian matrix - in this case, 6x6 - determined?

Thanks, but then what does it mean to take the mass-weighted Hessian - as Feynman does in the link - in other words, how does it make sense to say that M_i and M_j are the masses of the ith and jth degrees of freedom rather than the ith and jth atoms? And what would that be? Again, thanks for...

What do i and j stand for here? My teacher substituted them for masses (in our example, atoms in a molecule) although I'm not sure that makes sense since when you take the Hessian force constant matrix (on the next page of the link) I believe it must have dimensions determined by the number of...

How do you use the C_ij matrix to find the harmonic frequency (or frequencies) of a diatomic molecule, the OH (hydroxyl) radical? (I have no idea how to set it up for this.) This is from Feynmann's book on Statistical Mechanics...

How do you use the C_ij matrix to find the harmonic frequency (or frequencies) of a diatomic molecule, the OH (hydroxyl) radical? (I have no idea how to set it up for this.) This is from Feynmann's book on Statistical Mechanics...

How is stiffness affected by potential?

Find E(X) given the moment generating function M_X (t) = 1 / (1-t^2) for |t| < 1. (The pdf is f(x) = 0.5*exp(-|x|), for all x, so graphically you can see that E(X) should be 0.) ---- I know that E(X) = M ' _X (t) = 0 BUT M ' _X (t) = 2x / (1-x^2)^2 which is indeterminate at 0...