Recent content by ledol83

Hi...does anyone have a good description (or a link to it) on geodesic deviation equation?Most of the references i have are in a setting of relativity, which make me all at sea. Please help me if you know a mathematical characterization of how geodesics from one point deviate (which just...

thanks for your reply.

hi, why do you think geodesics are lines? According to Theodore Shifrin's book on line pp.86, for hyperbolic plane (u,v) equipped with metric tensor 1/v^2*I, the geodesics are not lines. I was just curious if any analytic relation between the geodesics and the lambda(x) function can be...

Hi there: i have a question on geodesics in a Eculidean space equipped with a metric tensor \lambda(x)*I, where I is the identity matrix. Is any general statement that can be made towards the geodesic between two points in this modified space? My feel is that this space is quite special...

i have realized that what i posed was not meaningful. i am now thinking over my problem again.. thanks!

it looks the method of characteristics only works for first-order equations, so i really don't know what it going on... i expected to convert to this format, but it doesn't work coz of the Fx,Fy terms: -grad.(c*grad(F))+aF=\lambda*d*f thanks so much for any help!

Hi actually i have f(x,y) and z(x,y) and was just wondering if this is true: df/dz=df/dx*dx/dz+df/dy*dy/dz thanks a lot!

you know exp(iwt)=cos(wt)+i*sin(wt); then you're right, triangle idents are needed. Just treat i as a constant, and it won't hurt other calculation.

You will need to integrate "this function times exp(i*omega*t)" over omega from -inf to +inf. The resulting thing is a function of t, which is in the time domain, as usually called.

hello! does anyone know how to solve the following (like an eigenvalue) PDE with matlab? aFxx+bFx+cFyy+dFy+eFxy=\lambda*F in which i am solving F with certain boundary conditions and a,b,c,d,e are functions independent of F. "pdeeig" in MATLAB doesn't seem to be able to handle...

Hi, i have a question on taking derivative w.r.t. to a function (instead of an independent variable). Actually i saw an excellent post on this same forum but that one was about a single variable. My question is: f is function of x and y, and z is some other function also dependent on x and y...