traj_to_grad.py
fe87d8e49f02master

traj_to_grad.py
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			from typing import Tuple

			import numpy as np

			from pypulseq.opts import Opts


			def traj_to_grad(k: np.ndarray, raster_time: float = Opts().grad_raster_time) -> Tuple[np.ndarray, np.ndarray]:
			"""
			Convert k-space trajectory `k` into gradient waveform in compliance with `raster_time` gradient raster time.

			Parameters
			----------
			k : numpy.ndarray
			K-space trajectory to be converted into gradient waveform.
			raster_time : float, optional, default=Opts().grad_raster_time
			Gradient raster time.

			Returns
			-------
			g : numpy.ndarray
			Gradient waveform.
			sr : numpy.ndarray
			Slew rate.
			"""
			g = (k[1:] - k[:-1]) / raster_time
			sr0 = (g[1:] - g[:-1]) / raster_time
			sr = np.zeros(len(sr0) + 1)
			sr[0] = sr0[0]
			sr[1:-1] = 0.5 * (sr0[-1] + sr0[1:])
			sr[-1] = sr0[-1]

			return g, sr