Forward — dmipy-sim

GPU Monte-Carlo of spins diffusing under an arbitrary free waveform G(t), with surface relaxivity, membrane permeability, and T2 baked into the walk. Magnetisation is treated as fully transverse (ideal instantaneous pulses).

import numpy as np, dmipy_sim as ds

wf = ds.set_b(ds.pgse(delta=5e-3, DELTA=20e-3, G_magnitude=0.05,
                      bvecs=np.array([[1., 0, 0]]), n_t=300), b_target=np.array([1e9]))
signal = ds.simulate(50_000, diffusivity=2e-9, waveform=wf,
                     geometry=ds.Cylinder(radius=5e-6, orientation=(0, 0, 1)))

Encodings: pgse, ogse, cpmg, ste, pte, trapezoidal_ogse. Multi-echo: simulate_cpmg(n_walkers, D, cpmg_waveform, geometry) returns the full CPMG echo train from a single walk. Geometries: FreeDiffusion, Box1D, Sphere, Cylinder, Ellipsoid, PackedCylinders, PackedSpheres, MyelinatedCylinder, PackedMyelinatedCylinders.

Every physical effect ships a first-principles 1D→2D→3D validation ladder against exact eigenvalues (see the repo's examples/validation/).