def interpolate(self, new_time, derivative_order=0, out=None):
new_time = np.asarray(new_time)
if new_time.ndim != 1:
raise ValueError(f"New time array must have exactly 1 dimension; it has {new_time.ndim}.")
new_shape = self.shape[:-2] + (new_time.size, self.shape[-1])
if out is not None:
out = np.asarray(out)
if out.shape != new_shape:
raise ValueError(
f"Output array should have shape {new_shape} for consistency with new time array and modes array"
)
if out.dtype != np.complex:
raise ValueError(f"Output array should have dtype `complex`; it has dtype {out.dtype}")
result = out or np.empty(new_shape, dtype=complex)
if derivative_order > 3:
raise ValueError(
f"{type(self)} interpolation uses CubicSpline, and cannot take a derivative of order {derivative_order}"
)
spline = CubicSpline(self.u, self.view(np.ndarray), axis=-2)
if derivative_order < 0:
spline = spline.antiderivative(-derivative_order)
elif 0 < derivative_order <= 3:
spline = spline.derivative(derivative_order)
result[:] = spline(new_time)
metadata = self._metadata.copy()
metadata["time"] = new_time
return type(self)(result, **metadata)
def calculate_position_with_time(x, speed):
poly = CubicSpline(x, speed, bc_type="natural")
antiderivative = poly.antiderivative()
return antiderivative(x)
