k-Wave Toolbox

fourierShift

Resample data using a Fourier interpolant.

Syntax

data = fourierShift(data, shift)
data = fourierShift(data, shift, dim)

Description

fourierShift resamples the input data along the dimension dim using a regular grid that is offset by the non-dimensional distance shift. The resampling is performed using a Fourier interpolant. This function can be used to shift the acoustic particle velocity recorded by the first-order simulation functions to the regular (non-staggered) temporal grid by setting shift to 1/2.

% define input function
dt      = pi/5;
t       = 0:dt:(2*pi - dt);
y       = cos(t);

% shift by 1/2 a grid point spacing
y_shift = fourierShift(y, 1/2);

% calculate exact function for reference
y_ref   = cos(t + dt/2);

% plot comparison
plot(t, y, 'k-s', t, y_shift, 'b-s', t, y_ref, 'rx');
legend('Original Function', 'Shifted Function', 'Reference', 'Location', 'north');

Inputs

data input data
shift non-dimensional shift, where 0 is no shift, 1/2 is for a staggered grid, and 1 is a full grid point

Optional Inputs

dim dimension over which the signals vary in time (default = highest non-singleton dimension)

Outputs

shifted_data shifted data

See Also

gradientSpect