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 Mar26 comment Fourier transform for dummies Here's a video I made a while ago describing the fourier series and fourier transform. It's a bit of a light hearted approach. youtube.com/watch?v=Qm84XIoTy0s May25 comment Submit papers: arxiv or vixra? I hate you people. I just spent an hour reading astrophysics papers on viXra. Who the hell is Jeffrey Joseph Wolynski? Woah! Apr24 comment Finding uncertainty in the slope/intercept for a non-linear least squares fit thanks again. I have finally worked through your solution and arrived as a $\pm$ value. See my updated question as I still have some queries I am uncertain of. Apr19 comment Finding uncertainty in the slope/intercept for a non-linear least squares fit Thanks for that. Just wanted to check that in your last equation you intended $\hat\sigma$ and not $\hat\sigma^2$. So $\hat\sigma$ is $\sqrt{\hat\sigma^2}$ Apr18 comment Finding uncertainty in the slope/intercept for a non-linear least squares fit Thanks for that. I'm not familiar with the notation, but it's making some sense. Wondering though, what is $\hat\sigma$ Apr8 comment Finding points along a plot in Matlab @macydanim: One more small question. What would I need in order to match a polynomial to it instead of finding a straight-line match? Apr8 comment Finding points along a plot in Matlab @macydanim Thanks once again. I've adapted it for my specific needs and it seems to work quite well. Thanks. Apr8 comment Finding points along a plot in Matlab @macydanim: This is a great help. When I replace your signal with the data I have though, it doesn't hit the points on the 50%/90% line. I'll update the question with my dataset. Apr8 comment Finding points along a plot in Matlab That Matt. That's a useful start for me. Much appreciated. How would I go about getting Matlab to approximate a gaussian curve to fit the signal? From that I should be able to interpolate the 20% and 50% points. Mar22 comment Solving the inverse of cos^2 Done. Keen for an edit on that if I have anything wrong. Thanks again for the guidance, it really helps to break these things down for me. Mar22 comment Solving the inverse of cos^2 Very helpful. Thanks for that Don. So after substituting the alternative, I can solve for i. I might update the question to include this as it's easier to do formulas in there. Mar22 comment Solving the inverse of cos^2 I'm just not familiar with the notation (was daydreaming during my trig classes unfortunately). So cos^2(i) is the same as [cos(i)]^2? Nov11 comment Finding outliers in a linear series Thanks for that Peter. I've used option 2 and the results are pretty clear to me now. Oct17 comment Finding the value which minimises all residuals Excellent. Thank you very much for that explanation. It helps immensely. Oct17 comment Finding the value which minimises all residuals Thanks Ross. A few things are confusing me here ... Shouldn't I be calculating $tan(\Delta RA)$ at each time, and comparing it with the result of the right term of the model? I then get the differences between the observed results and the model predicted results (right term), sum of their squares, and try to minimise that sum by Goal Seeking for different values of $R$. Does that sound right to you? Sep29 comment Multiple variables with multiple solutions Hi Berci. Thanks for that idea too. I would love to add in another condition, but in this particular instance, I can't. Otherwise it might certainly make it easier to restrict the values of $x, y, z$. Sep29 comment Multiple variables with multiple solutions Thanks for the further explanation. That makes sense now. Yes, $x, y, z \ge 0$. I guess rearranging the equation to solve for $x$ or $y$ would be tricky? Sep29 comment Multiple variables with multiple solutions Thanks for that Alex. That makes a little sense, rearranging it like that. The part I'm unclear of is what I do with the $x, y,$ at the start? Are they just multiplied in? Plugging in values of $x=3, y=1$, how might it work? (sorry if this is a really basic question) May20 comment Determining the error from a list of individual errors I've clarified by question a little by removing "average error" as I don't think that's what I'm after exactly. What I need to work out is the error of the whole dataset when averaged. May19 comment Determining the error from a list of individual errors I understand how to get a standard mean error (stdev / sqrt(number-of-values), but I'm not sure I understand the average squared error you mentioned. How would I calculate that given my example?