Sequence.mod_grad_axis

Sequence.mod_grad_axis()

Scale the amplitude of every gradient on axis by modifier.

Parameters:

• axis ({'x', 'y', 'z'}) – Which axis to act on.

• modifier (float) – What to multiply by. -1 inverts the axis, 0 silences it.

Raises:

• ValueError – If axis is not one of ‘x’, ‘y’ or ‘z’.

• RuntimeError – If a gradient is played both on axis and on another, where there is no one answer.

Notes

Only the amplitude moves. The ramps, the delay and the shape stay as they are, so the areas scale with the amplitude and the timing does not change.

Silencing the phase encoding is mod_grad_axis('y', 0.0); inverting the readout is mod_grad_axis('x', -1.0).

Examples

>>> import pypulseqpp as pp
>>> seq = pp.Sequence(pp.Opts())
>>> seq.add_block(pp.make_trapezoid("x", area=1000, duration=2e-3))
1
>>> seq.mod_grad_axis("x", 0.5)
>>> seq.get_block(1).gx.area
500.0