Someone asked me a question via e-mail about integer partitions the other day (as I had released a Perl module, Integer::Partition, to generate them), that I was unable to answer. Background: here are all the integer partitions of 7 (the sum of each row equals 7). 7 6 1 5 2 5 1 1 4 3 4 2 1 4 1 1 1 3 3 1 3 2 2 3 2 1 1 3 1 1 1 1 2 2 2 1 ...
The curve-fitting problem for 2D data is well known (LOWESS, etc.) but given a set of 3D data points, how do I fit a 3D curve (eg. a smoothing/regression spline) to this data? MORE: I'm trying to find a curve, fitting the data provided by vectors X,Y,Z which have no known relation. Essentially, I have a 3D point cloud, and need to find...
I have three X/Y points that form a parabola. I simply need to calculate what the vertex of the parabola is that goes through these three points. Preferably a quick way as I have to do a LOT of these calculations! The "Ask A Scientist" website provides this answer: The general form of a parabola is given by the equation: A * x^2 + B...
I am trying to write C++ function perform curve fitting implementation using least square method. Input parameters of this function are x and y 1D array and n. And this function finds the coefficients of a polynomial p(x) of degree n that fits the data, p(x(i)) to y(i), in a least squares sense. Therefore, function will return coeffic...
I'm hoping to find a simple library that can take a series of 2 dimensional points and give me back a larger series of points that model the curve. Basically, I want to get the effect of curve fitting like this sample from JFreeChart: The problem with JFreeChart is that the code does not provide this type of api. I even looked at the ...
I'm using Python and Numpy to calculate a best fit polynomial of arbitrary degree. I pass a list of x values, y values, and the degree of the polynomial I want to fit (linear, quadratic, etc.). This much works, but I also want to calculate r (coefficient of correlation) and r-squared(coefficient of determination). I am comparing my re...
Question: How do you fit a curve to points on a plane if they aren't single valued? For the example shown, how would one fit a curve (like the black one) to the noisy blue data? It's similar to spline smoothing, but I don't know the order of the data. Matlab would be preferred, but pseudocode is fine. Or a pointer to what the correc...
Im a programmer that wants to learn how the Levenberg–Marquardt curvefitting algorithm works so that i can implement it myself. Is there a good tutorial anywhere that can explain how it works in detail with the reader beeing a programmer and not a mathemagician. My goal is to implement this algorithm in opencl so that i can have it run ...
What functions do you use in R to fit a curve to your data and test how well that curve fits? What results are considered good? ...
I need to make a topographic map of a terrain for which I have only fairly sparse samples of (x, y, altitude) data. Obviously I can't make a completely accurate map, but I would like one that is in some sense "smooth". I need to quantify "smoothness" (probably the reciprocal the average of the square of the surface curvature) and I wan...
I'm looking for a non-linear curve fitting routine (probably most likely to be found in R or Python, but I'm open to other languages) which would take x,y data and fit a curve to it. I should be able to specify as a string the type of expression I want to fit. Examples: "A+B*x+C*x*x" "(A+B*x+C*x*x)/(D*x+E*x*x)" "sin(A+B*x)*exp(C+D*x)+...
we have to fit about 2000 or odd time series every month, they have very idiosyncratic behavior in particular, some are arma/arima, some are ewma, some are arch/garch with or without seasonality and/or trend (only thing in common is the time series aspect). one can in theory build ensemble model with aic or bic criterion to choose the b...
Is there a function in R that fits a curve to a histogram? Let's say you had the following histogram hist(c(rep(65, times=5), rep(25, times=5), rep(35, times=10), rep(45, times=4))) It looks normal, but it's skewed. I want to fit a normal curve that is skewed to wrap around this histogram. This question is rather basic, but I can't ...
I am trying to fit a step function using scipy.optimize.leastsq. Consider the following example: import numpy as np from scipy.optimize import leastsq def fitfunc(p, x): y = np.zeros(x.shape) y[x < p[0]] = p[1] y[p[0] < x] = p[2] return y errfunc = lambda p, x, y: fitfunc(p, x) - y # Distance to the target function x ...
This isn't really OCR, since it's not recognizing characters, but it's the same idea. Anyone know of an image-processing library or established algorithm for retrieving the values from a (raster) plot image? For instance, in this graph, it's hard for me to read exact values with my eyes because there's such gaps between gridlines: I...
I would like to do an algebraic curve fit of 2D data points, but for various reasons - it isn't really possible to have much of the sample data in memory at once, and iterating through all of it is an expensive process. (The reason for this is that actually I need to fit thousands of curves simultaneously based on gigabytes of data whic...
I'm a developer up in Portland, OR. I'm wondering if anyone can assist: I'm working on Loess fit models using R, once I have the fit accomplished, I'm looking to back-out the equation of the fitted non-linear curve, wondering if there is a way to determine this equation in R? I've been looking but can't find any literature. For me, the ...
I am using Bezier curves to plot curves in a program I am making. I have five points. Here is a crude sketch of the curve I am trying to create. I'm trying to make a curve that goes through A,B,C,D. However, C is not a definite point, it is a suggestion of where the curve should pass through to make it look like a French Curve. C com...
I have two questions concerning fitting a gauss curve to histogram peaks. My first question is a very basic one: How can I fit a gauss curve to a entire histogram? Does this only mean that I have to find out and calculate the mean value(µ) and the deviation(ϭ) of the histogram and put them into the formula for the Gauss curve? Would ...
I have a gray-scale image and I want to make a function that closely follows the image is always grater than it the image smooth at some given scale. In other words I want a smooth function that approximates the maximum of another function in the local region while over estimating the that function at all points. Any ideas? My...