scaleGrad

Scales a gradient waveform by a given scalar value. It handles both trapezoidal and arbitrary waveforms. Optionally, it checks the scaled gradient against system limits (maximum gradient amplitude and slew rate) to prevent exceeding hardware capabilities.

Syntax

function [grad] = scaleGrad(grad, scale, system)

Calling Pattern

mr.scaleGrad(...)

Parameters

Required Parameters

Name	Type	Description	Example	Units
grad	struct	Structure containing the gradient waveform to be scaled. For trapezoidal gradients, it contains fields like 'amplitude', 'area', 'flatArea', 'riseTime', and 'fallTime'. For arbitrary waveforms, it contains fields like 'waveform' and 'tt'.	{type: 'trap', amplitude: 10, area: 0.001, flatArea: 0.0005, riseTime: 0.001, fallTime: 0.001}
scale	double	Scalar value by which to scale the gradient waveform.	2.5

Optional Parameters

Name	Type	Default	Description	Example
system	struct	N/A	Structure containing system limits. Must contain fields 'maxGrad' (maximum gradient amplitude in Hz/m) and 'maxSlew' (maximum slew rate in Hz/m/s). Valid values: Must be a struct with 'maxGrad' and 'maxSlew' fields.	{maxGrad: 40e6, maxSlew: 150e6}

Returns

Output	Type	Description
grad	struct	The scaled gradient waveform structure. The 'id' field, if present, will be removed.

Examples

% Reverse gradient polarity for EPI readout alternation
gx = mr.scaleGrad(gx, -1);

% Scale phase encoding gradient for different k-space steps
seq.addBlock(gxPre, mr.scaleGrad(gyPre, peScales(i)), gzReph);

% Create rewinding gradient with opposite polarity
gpe2jr = mr.scaleGrad(gpe2, -pe2Steps(count));

See Also

makeTrapezoid