MATLAB: Simultaneous fitting of two plots with two functions

curve fittingMATLAB

I have two sets of dependent variable column vectors (y1, y2) for a set of independent variable column vectors (x). I want to fit the (x, y1) plot with the function f1(ca. f1 = (a + (b-a)*(1 + c*x^d))) and the (x, y2) plot with the function f2(ca. f2 = (b-a)*c*x^d)) simultaneously. Could anyone please help?

Many thanks, in advance! Arun

Best Answer

Use "lsqcurvefit" with the data set xdata = (x,x),ydata = (y1,y2).

Best wishes

Torsten.

Related Solutions

MATLAB: Optimizing systems of non-linear equation using optimvar and lsqcurvefit

Your ‘fun’ function will work, providing the dependent variable matrix is (3xN), and ‘y1’. ‘y2’ and ‘y3’ are row vectors.

Assuming that, the dependent variables (as row vectors) need to be in a matrix, so that there is one variable for ‘y’, not three.

Try this:

ymtx = [y1; y2; y3];
x = lsqcurvefit(fun,x0,xdata,ymtx,[],[],options)

The error arises because in the code youi posted, ‘y2’ and ‘y3’ appear in the positions in the lsqcurvefit argument list reserved for the bounds vectors.

MATLAB: How to use the ‘least square fit’

xdata = 0:0.51:195*0.51;
ydata = ...;
fun = @(x,xdata)x(1)*sin(x(2)*xdata.^x(3)+x(4)).*exp(-x(5)*xdata)+x(6);
x0 = [-6 ,1 ,1 ,0 ,0 ,0];
x = lsqcurvefit(fun,x0,xdata,ydata)

Best Answer

Related Solutions

MATLAB: Optimizing systems of non-linear equation using optimvar and lsqcurvefit

MATLAB: How to use the ‘least square fit’

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