Signals will be poorly represented at the edges.
The function signal is assumed to be periodic, and so non-periodic There are two significant limitations on Fourier interpolation. Interpft assumes that the interpolated function is periodic,Īnd so assumptions are made about the end points of the interpolation. If x is an array, then operate along each column of The data in x is assumed to beĮquispaced. However, if the function to be evaluated is in some mannerĭiscontinuous, then 'pchip' interpolation might give better results.įourier interpolation, is a resampling technique where a signal isĬonverted to the frequency domain, padded with zeros and thenįunction File: interpft ( x, n) Function File: interpft ( x, n, dim)įourier interpolation. Interpolated is in fact smooth, then 'spline' will give excellent The 'spline' method enforces that both the first and secondĭerivatives of the interpolated values have a continuous derivative, There are some important differences between the various interpolation Legend ("original","linear","spline","cubic","nearest")
There is an equivalence, such that ppval (interp1 ( x, Supplied and interp1 returns the piece-wise polynomial thatĬan later be used with ppval to evaluate the interpolation. If the string argument 'pp' is specified, then xi should not be If extrap is a number, replace values beyond theĮndpoints with that number. If extrap is the string 'extrap', then extrapolate values beyond This is usually faster,Īnd is never slower. To assume that x is uniformly spaced, and only x Piece-wise cubic hermite interpolating polynomialĬubic interpolation from four nearest neighboursĬubic spline interpolation-smooth first and second derivativesĪppending '*' to the start of the above method forces interp1 Linear interpolation from nearest neighbours section 26.5 Polynomial InterpolationĪnd section 28.4 Interpolation on Scattered Data describe further methods.įunction File: yi = interp1 ( x, y, xi) Function File: yi = interp1 (., method) Function File: yi = interp1 (., extrap) Function File: pp = interp1 (., 'pp') Octave supports several methods for one-dimensional interpolation, most