Recent content by stevenphy2

Adding them and divide it by the total number of samples will work only if my signal is of complete periods, right? For example, if my full signal is a cosine wave, but I just have data that are half of the wavelength, it will not give me an average of zero. I am wondering if there is...

Hi all, I have discrete data of a signal but I do not know the periods of the signal. The signal is like a "beat" I guess, but not really sure. I plan to use fft in MATLAB to get it's frequency spectrum and get the 0Hz value as the average of the signal. Is this a bad idea? Any other ways...

Hi all, if I have the velocities and rotations of an object with respect to a moving frame. Are there relations that I can obtain the velocities and rotations of the object with respect to a fixed frame?

Hi all, let's say I have generated some discrete data as a function of time. And when I plot it, it looks like that it is periodic. Is there any scientific way to check whether or not the discrete data is really periodic? And determine the period, if possible? Many thanks.

Hi all, as title, how to take the power of elements of an array to, say, 5? I know how to do it using loops, but would it be very troublesome if I have to do it a thousand times? Any ready made function in fortran90? I hope there is... I have googled it quite a bit, but seems nothing useful.

HallsofIvy, thanks. That's what I meant. I think it is the way to go, but I do not know things like "binormal" etc. I should learn it now. Do you have textbooks to recommend for learning these things? Or standard text which teach you how to do these super helices things? Thanks.

So, I mean the mathematical description of a super-helix.

hi all, I am wondering how to mathematically describe a curve formed by having a helix tracing out a helical trajectory? Any idea?