Mercurial > octave
view scripts/general/interpft.m @ 27985:9f9ac219896d
maint: Remove remaining "Author:" instances from code base.
* __ftp__.cc, load-save.cc, urlwrite.cc, xnorm.cc, xnorm.h, cconv2.f,
cdotc3.f, cmatm3.f, csconv2.f, dconv2.f, ddot3.f, dmatm3.f, sconv2.f, sdot3.f,
smatm3.f, zconv2.f, zdconv2.f, zdotc3.f, zmatm3.f, crsf2csf.f, zrsf2csf.f,
oct-norm.cc, oct-norm.h, lin2mu.m, mu2lin.m, bincoeff.m, blkdiag.m, deal.m,
gradient.m, interpft.m, nextpow2.m, postpad.m, prepad.m, repmat.m, shift.m,
xor.m, griddata.m, rotx.m, roty.m, rotz.m, voronoin.m, getappdata.m,
isappdata.m, rmappdata.m, setappdata.m, colormap.m, gray.m, gray2ind.m,
im2double.m, image.m, imagesc.m, imread.m, imshow.m, ind2gray.m, ind2rgb.m,
ocean.m, __imread__.m, rgb2ind.m, javachk.m, ClassHelper.java, usejava.m,
findstr.m, commutation_matrix.m, cross.m, gls.m, housh.m, isdefinite.m,
ishermitian.m, issymmetric.m, logm.m, null.m, ols.m, orth.m, qzhess.m, rref.m,
dos.m, nargoutchk.m, orderfields.m, parseparams.m, __w2mpth__.m, unix.m,
untar.m, unzip.m, expand_rel_paths.m, make_rel_paths.m, daspect.m, orient.m,
pbaspect.m, rticks.m, thetaticks.m, xticklabels.m, xticks.m, yticklabels.m,
yticks.m, zticklabels.m, zticks.m, comet.m, contourf.m, plot3.m, cla.m,
copyobj.m, findfigs.m, hdl2struct.m, linkaxes.m, __ghostscript__.m,
__gnuplot_get_var__.m, __gnuplot_has_feature__.m, __gnuplot_has_terminal__.m,
__gnuplot_open_stream__.m, __gnuplot_print__.m, struct2hdl.m, subplot.m,
compan.m, conv.m, deconv.m, mpoles.m, poly.m, polyder.m, polyfit.m, polyint.m,
polyout.m, polyreduce.m, polyval.m, polyvalm.m, residue.m, roots.m, ismember.m,
__parse_movargs__.m, detrend.m, fftconv.m, fftfilt.m, fftshift.m, filter2.m,
movfun.m, movslice.m, ichol.m, pcg.m, beta.m, ellipke.m, lcm.m, nchoosek.m,
pow2.m, primes.m, pascal.m, rosser.m, wilkinson.m, corr.m, kurtosis.m,
skewness.m, base2dec.m, bin2dec.m, blanks.m, deblank.m, dec2base.m, dec2bin.m,
dec2hex.m, hex2dec.m, index.m, rindex.m, strjoin.m, substr.m, untabify.m,
calendar.m, datestr.m, eomday.m, now.m, weekday.m:
Remove remaining "Author:" instances from code base.
author | Rik <rik@octave.org> |
---|---|
date | Tue, 21 Jan 2020 14:35:03 -0800 |
parents | c20b7290c778 |
children | 28de41192f3c 0a5b15007766 |
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######################################################################## ## ## Copyright (C) 2001-2020 The Octave Project Developers ## ## See the file COPYRIGHT.md in the top-level directory of this ## distribution or <https://octave.org/copyright/>. ## ## This file is part of Octave. ## ## Octave is free software: you can redistribute it and/or modify it ## under the terms of the GNU General Public License as published by ## the Free Software Foundation, either version 3 of the License, or ## (at your option) any later version. ## ## Octave is distributed in the hope that it will be useful, but ## WITHOUT ANY WARRANTY; without even the implied warranty of ## MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the ## GNU General Public License for more details. ## ## You should have received a copy of the GNU General Public License ## along with Octave; see the file COPYING. If not, see ## <https://www.gnu.org/licenses/>. ## ######################################################################## ## -*- texinfo -*- ## @deftypefn {} {} interpft (@var{x}, @var{n}) ## @deftypefnx {} {} interpft (@var{x}, @var{n}, @var{dim}) ## ## Fourier interpolation. ## ## If @var{x} is a vector then @var{x} is resampled with @var{n} points. The ## data in @var{x} is assumed to be equispaced. If @var{x} is a matrix or an ## N-dimensional array, the interpolation is performed on each column of ## @var{x}. ## ## If @var{dim} is specified, then interpolate along the dimension @var{dim}. ## ## @code{interpft} assumes that the interpolated function is periodic, and so ## assumptions are made about the endpoints of the interpolation. ## @seealso{interp1} ## @end deftypefn function z = interpft (x, n, dim) if (nargin < 2 || nargin > 3) print_usage (); endif if (! (isscalar (n) && n == fix (n))) error ("interpft: N must be a scalar integer"); endif if (nargin == 2) if (isrow (x)) dim = 2; else dim = 1; endif endif nd = ndims (x); if (dim < 1 || dim > nd) error ("interpft: invalid dimension DIM"); endif perm = [dim:nd, 1:(dim-1)]; x = permute (x, perm); m = rows (x); inc = ceil (m/n); y = fft (x) / m; k = ceil (m / 2); sz = size (x); sz(1) = n * inc - m; idx = repmat ({':'}, nd, 1); idx{1} = 1:k; z = cat (1, y(idx{:}), zeros (sz)); idx{1} = k+1:m; z = cat (1, z, y(idx{:})); ## When m is an even number of rows, the FFT has a single Nyquist bin. ## If zero-padded above, distribute the value of the Nyquist bin evenly ## between the new corresponding positive and negative frequency bins. if (sz(1) > 0 && k == m/2) idx{1} = n * inc - k + 1; tmp = z(idx{:}) / 2; z(idx{:}) = tmp; idx{1} = k + 1; z(idx{:}) = tmp; endif z = n * ifft (z); if (inc != 1) sz(1) = n; z = inc * reshape (z(1:inc:end), sz); endif z = ipermute (z, perm); endfunction %!demo %! clf; %! t = 0 : 0.3 : pi; dt = t(2)-t(1); %! n = length (t); k = 100; %! ti = t(1) + [0 : k-1]*dt*n/k; %! y = sin (4*t + 0.3) .* cos (3*t - 0.1); %! yp = sin (4*ti + 0.3) .* cos (3*ti - 0.1); %! plot (ti, yp, 'g', ti, interp1(t, y, ti, "spline"), 'b', ... %! ti, interpft (y, k), 'c', t, y, "r+"); %! legend ("sin(4t+0.3)cos(3t-0.1)", "spline", "interpft", "data"); %!shared n,y %! x = [0:10]'; y = sin(x); n = length (x); %!testif HAVE_FFTW %! assert (interpft (y, n), y, 20*eps) %!testif HAVE_FFTW %! assert (interpft (y', n), y', 20*eps) %!testif HAVE_FFTW %! assert (interpft ([y,y],n), [y,y], 20*eps) ## Test case with complex input %!testif HAVE_FFTW <*39566> %! x = (1 + j) * [1:4]'; %! y = ifft ([15 + 15*j; -6; -1.5 - 1.5*j; 0; -1.5 - 1.5*j; -6*j]); %! assert (interpft (x, 6), y, 10*eps); ## Test for correct spectral symmetry with even/odd lengths %!testif HAVE_FFTW %! assert (max (abs (imag (interpft ([1:8], 20)))), 0, 20*eps) %!testif HAVE_FFTW %! assert (max (abs (imag (interpft ([1:8], 21)))), 0, 21*eps) %!testif HAVE_FFTW %! assert (max (abs (imag (interpft ([1:9], 20)))), 0, 20*eps) %!testif HAVE_FFTW %! assert (max (abs (imag (interpft ([1:9], 21)))), 0, 21*eps) ## Test input validation %!error interpft () %!error interpft (1) %!error interpft (1,2,3) %!error <N must be a scalar integer> interpft (1,[2,2]) %!error <N must be a scalar integer> interpft (1,2.1) %!error <invalid dimension DIM> interpft (1,2,0) %!error <invalid dimension DIM> interpft (1,2,3)