MATLAB: Polyfit with odd powers only

datanonlineartransfer function

Hi,
I am trying to get a polyfit with only odd powers – so polyfit will not work because it has odd and even.
I do not have the curve fitting toolbox.
Is there another function of lines of code that will do this? I've searched around and read topics but cant seem to get it working…
x = [-50 -49.9 -49.7 -49.6 -49.4 -49.3 -49.1 -49 -48.8 -48.7 -48.6 -48.4 -48.3 -48.1 -48 -47.8 -47.7 -47.5 -47.4 -47.2 -47.1 -47 -46.8 -46.7 -46.5 -46.4 -46.2 -46.1 -45.9 -45.8 -45.7 -45.5 -45.4 -45.2 -45.1 -44.9 -44.8 -44.6 -44.5 -44.3 -44.2 -44.1 -43.9 -43.8 -43.6 -43.5 -43.3 -43.2 -43 -42.9 -42.8 -42.6 -42.5 -42.3 -42.2 -42 -41.9 -41.7 -41.6 -41.4 -41.3 -41.2 -41 -40.9 -40.7 -40.6 -40.4 -40.3 -40.1 -40 -39.9 -39.7 -39.6 -39.4 -39.3 -39.1 -39 -38.8 -38.7 -38.5 -38.4 -38.3 -38.1 -38 -37.8 -37.7 -37.5 -37.4 -37.2 -37.1 -37 -36.8 -36.7 -36.5 -36.4 -36.2 -36.1 -35.9 -35.8 -35.6 -35.5 -35.4 -35.2 -35.1 -34.9 -34.8 -34.6 -34.5 -34.3 -34.2 -34.1 -33.9 -33.8 -33.6 -33.5 -33.3 -33.2 -33 -32.9 -32.7 -32.6 -32.5 -32.3 -32.2 -32 -31.9 -31.7 -31.6 -31.4 -31.3 -31.2 -31 -30.9 -30.7 -30.6 -30.4 -30.3 -30.1 -30 -29.8 -29.7 -29.6 -29.4 -29.3 -29.1 -29 -28.8 -28.7 -28.5 -28.4 -28.3 -28.1 -28 -27.8 -27.7 -27.5 -27.4 -27.2 -27.1 -26.9 -26.8 -26.7 -26.5 -26.4 -26.2 -26.1 -25.9 -25.8 -25.6 -25.5 -25.4 -25.2 -25.1 -24.9 -24.8 -24.6 -24.5 -24.3 -24.2 -24 -23.9 -23.8 -23.6 -23.5 -23.3 -23.2 -23 -22.9 -22.7 -22.6 -22.5 -22.3 -22.2 -22 -21.9 -21.7 -21.6 -21.4 -21.3 -21.1 -21];
y = [-24.75097 -24.67164 -24.4801 -24.3577 -24.16221 -24.07226 -23.8446 -23.74222 -23.54947 -23.44198 -23.34674 -23.1479 -23.02214 -22.84665 -22.73298 -22.54093 -22.42616 -22.22016 -22.12129 -21.92824 -21.83178 -21.72892 -21.51621 -21.42578 -21.21406 -21.11511 -20.91655 -20.82348 -20.60448 -20.51302 -20.41675 -20.21547 -20.11611 -19.92628 -19.81589 -19.62125 -19.51582 -19.31288 -19.21443 -19.01194 -18.91046 -18.82235 -18.62306 -18.52276 -18.31691 -18.21565 -18.01884 -17.91986 -17.7219 -17.62982 -17.53392 -17.32261 -17.22725 -17.02708 -16.92875 -16.72639 -16.62719 -16.42994 -16.32574 -16.12839 -16.03569 -15.93901 -15.73049 -15.62979 -15.44024 -15.33308 -15.14062 -15.04554 -14.83767 -14.74988 -14.64451 -14.44684 -14.34319 -14.14475 -14.05439 -13.85229 -13.75652 -13.55815 -13.45882 -13.25949 -13.17189 -13.06923 -12.8671 -12.77876 -12.57822 -12.48735 -12.29286 -12.19462 -12.00186 -11.91447 -11.81787 -11.63201 -11.54073 -11.34952 -11.27196 -11.0899 -11.00039 -10.82415 -10.74487 -10.57193 -10.49104 -10.40562 -10.24737 -10.16286 -10.00381 -9.92581 -9.77272 -9.70086 -9.53765 -9.47072 -9.39156 -9.24676 -9.17277 -9.02883 -8.96238 -8.82083 -8.75691 -8.62635 -8.5598 -8.44304 -8.38449 -8.32837 -8.21934 -8.16412 -8.05312 -8.00186 -7.90721 -7.85077 -7.74586 -7.69695 -7.63831 -7.53163 -7.48072 -7.37289 -7.32272 -7.21067 -7.15707 -7.05749 -7.01419 -6.9207 -6.88097 -6.84193 -6.77068 -6.74107 -6.6824 -6.65511 -6.60911 -6.58551 -6.54557 -6.51723 -6.503 -6.46382 -6.44574 -6.39763 -6.38649 -6.34661 -6.33092 -6.29201 -6.27877 -6.2389 -6.22502 -6.20754 -6.17015 -6.15153 -6.11958 -6.10592 -6.06368 -6.05479 -6.023 -6.00659 -5.99346 -5.96016 -5.94925 -5.9124 -5.90166 -5.87321 -5.85589 -5.82928 -5.82597 -5.7912 -5.77671 -5.76612 -5.73985 -5.731 -5.71439 -5.70532 -5.67559 -5.66804 -5.6418 -5.63944 -5.63151 -5.61857 -5.60494 -5.58464 -5.58045 -5.55205 -5.54998 -5.52862 -5.52516 -5.50865 -5.50969];
Please can someone assist

Best Answer

x = [ ... ];
y = [ ... ];
x = x.';
y = y.';
n = 5; % degree of polynomial p ; n must be odd
A = [];
for i = 1:2:n
A = [A x.^i];
end
coeff = A\y % Polynomial is given by p(z)=coeff(1)*z + coeff(2)*z^3 + ... + coeff((n+1)/2)*z^n
Best wishes
Torsten.