restoreAdditionalShapeSamples

This function post-processes a gradient waveform, specifically addressing issues that can arise when trapezoidal gradients are converted into arbitrary shapes. It aims to restore samples at the edges of gradient raster intervals to ensure accuracy. The function identifies and corrects discrepancies between the reconstructed waveform and the original, particularly important in situations like spiral gradients where small deviations can occur.

Syntax

function [tt_chg, waveform_chg] = restoreAdditionalShapeSamples(tt,waveform,first,last,gradRasterTime,iBlock)

Calling Pattern

mr.restoreAdditionalShapeSamples(...)

Parameters

Required Parameters

Name	Type	Description	Example	Units
tt	double	Time vector corresponding to the original gradient waveform.	[0 0.001 0.002 0.003]	seconds
waveform	double	Original gradient waveform amplitude values.	[0 100 100 0]	Hz/m
first	double	Amplitude of the first sample of the original gradient waveform.	0	Hz/m
last	double	Amplitude of the last sample of the original gradient waveform.	0	Hz/m
gradRasterTime	double	Time interval of the gradient raster.	0.000001	seconds
iBlock	double	Index of the current block (optional, used for warning messages).	1

Returns

Output	Type	Description
tt_chg	double	Modified time vector after shape restoration.
waveform_chg	double	Modified gradient waveform after shape restoration.

Examples

% Basic shape restoration
tt = [0, 1e-3, 2e-3, 3e-3];
waveform = [0, 100, 100, 0];
[tt_chg, waveform_chg] = mr.restoreAdditionalShapeSamples(tt, waveform, 0, 0, 1e-6, 1);

% Restore gradient shape samples
[tt_restored, waveform_restored] = mr.restoreAdditionalShapeSamples(grad.tt, grad.waveform, ...
                                                                   grad.first, grad.last, ...
                                                                   gradRasterTime, blockIndex);

% Process arbitrary gradient waveform
if ~isempty(grad.tt)
    [tt_chg, waveform_chg] = mr.restoreAdditionalShapeSamples(grad.tt, grad.waveform, ...
                                                             grad.first, grad.last, ...
                                                             obj.gradRasterTime, iBc);
end