def dipole(src,
rec,
depth,
res,
freqtime,
aniso=None,
eperm=None,
mperm=None,
verb=2):
r"""Return the electromagnetic field due to a dipole source.
This is a modified version of ``empymod.model.dipole()``. It returns the
separated contributions of TM--, TM-+, TM+-, TM++, TMdirect, TE--, TE-+,
TE+-, TE++, and TEdirect.
Parameters
----------
src, rec : list of floats or arrays
Source and receiver coordinates (m): [x, y, z].
The x- and y-coordinates can be arrays, z is a single value.
The x- and y-coordinates must have the same dimension.
Sources or receivers placed on a layer interface are considered in the
upper layer.
Sources and receivers must be in the same layer.
depth : list
Absolute layer interfaces z (m); #depth = #res - 1
(excluding +/- infinity).
res : array_like
Horizontal resistivities rho_h (Ohm.m); #res = #depth + 1.
freqtime : float
Frequency f (Hz). (The name ``freqtime`` is kept for consistency with
``empymod.model.dipole()``. Only one frequency at once.
aniso : array_like, optional
Anisotropies lambda = sqrt(rho_v/rho_h) (-); #aniso = #res.
Defaults to ones.
eperm : array_like, optional
Relative electric permittivities epsilon (-);
#eperm = #res. Default is ones.
mperm : array_like, optional
Relative magnetic permeabilities mu (-);
#mperm = #res. Default is ones.
verb : {0, 1, 2, 3, 4}, optional
Level of verbosity, default is 2:
- 0: Print nothing.
- 1: Print warnings.
- 2: Print additional runtime and kernel calls
- 3: Print additional start/stop, condensed parameter information.
- 4: Print additional full parameter information
Returns
-------
TM, TE : list of ndarrays, (nfreq, nrec, nsrc)
Frequency-domain EM field [V/m], separated into
TM = [TM--, TM-+, TM+-, TM++, TMdirect]
and
TE = [TE--, TE-+, TE+-, TE++, TEdirect].
However, source and receiver are normalised. So the source strength is
1 A and its length is 1 m. Therefore the electric field could also be
written as [V/(A.m2)].
The shape of EM is (nfreq, nrec, nsrc). However, single dimensions
are removed.
"""
# === 1. LET'S START ============
t0 = printstartfinish(verb)
# === 2. CHECK INPUT ============
# Check layer parameters
model = check_model(depth, res, aniso, eperm, eperm, mperm, mperm, False,
verb)
depth, res, aniso, epermH, epermV, mpermH, mpermV, _ = model
# Check frequency => get etaH, etaV, zetaH, and zetaV
frequency = check_frequency(freqtime, res, aniso, epermH, epermV, mpermH,
mpermV, verb)
freq, etaH, etaV, zetaH, zetaV = frequency
# Check src and rec
src, nsrc = check_dipole(src, 'src', verb)
rec, nrec = check_dipole(rec, 'rec', verb)
# Get offsets
off, ang = get_off_ang(src, rec, nsrc, nrec, verb)
# Get layer number in which src and rec reside (lsrc/lrec)
lsrc, zsrc = get_layer_nr(src, depth)
lrec, zrec = get_layer_nr(rec, depth)
# Check limitations of this routine compared to the standard ``dipole``
if lsrc != lrec: # src and rec in same layer
print("* ERROR :: src and rec must be in the same layer; " +
"<lsrc>/<lrec> provided: " + str(lsrc) + "/" + str(lrec))
raise ValueError('src-z/rec-z')
if depth.size < 2: # at least two layers
print("* ERROR :: model must have more than one layer; " +
"<depth> provided: " + _strvar(depth[1:]))
raise ValueError('depth')
if freq.size > 1: # only 1 frequency
print("* ERROR :: only one frequency permitted; " +
"<freqtime> provided: " + _strvar(freqtime))
raise ValueError('frequency')
# === 3. EM-FIELD CALCULATION ============
# This part is a simplification of:
# - model.fem()
# - transform.dlf()
# - kernel.wavenumber()
# DLF filter we use
filt = key_201_2012()
# 3.1. COMPUTE REQUIRED LAMBDAS for given hankel-filter-base
lambd = filt.base / off[:, None]
# 3.2. CALL THE KERNEL
PTM, PTE = greenfct(zsrc, zrec, lsrc, lrec, depth, etaH, etaV, zetaH,
zetaV, lambd)
# 3.3. CARRY OUT THE HANKEL TRANSFORM WITH DLF
factAng = angle_factor(ang, 11, False, False)
zmfactAng = (factAng[:, np.newaxis] - 1) / 2
zpfactAng = (factAng[:, np.newaxis] + 1) / 2
fact = 4 * np.pi * off
# TE [uu, ud, du, dd, df]
for i, val in enumerate(PTE):
PTE[i] = (factAng * np.dot(-val, filt.j1) / off +
np.dot(zmfactAng * val * lambd, filt.j0)) / fact
# TM [uu, ud, du, dd, df]
for i, val in enumerate(PTM):
PTM[i] = (factAng * np.dot(-val, filt.j1) / off +
np.dot(zpfactAng * val * lambd, filt.j0)) / fact
# 3.4. Remove non-physical contributions
# (Note: The T*dd corrections differ slightly from the equations given in
# the accompanying pdf, due to the way the direct field is accounted for
# in the book.)
# General parameters
Gam = np.sqrt((zetaH * etaH)[:, None, :, None]) # Gam for lambd=0
iGam = Gam[:, :, lsrc, 0]
lgam = np.sqrt(zetaH[:, lsrc] * etaH[:, lsrc])
ddepth = np.r_[depth, np.inf]
ds = ddepth[lsrc + 1] - ddepth[lsrc]
def get_rp_rm(z_eta):
r"""Return Rp, Rm."""
# Get Rp/Rm for lambd=0
Rp, Rm = reflections(depth, z_eta, Gam, lrec, lsrc, False)
# Depending on model Rp/Rm have 3 or 4 dimensions. Last two are
# wavenumbers and layers btw src and rec, which both are 1.
if Rp.ndim == 4:
Rp = np.squeeze(Rp, axis=3)
if Rm.ndim == 4:
Rm = np.squeeze(Rm, axis=3)
Rp = np.squeeze(Rp, axis=2)
Rm = np.squeeze(Rm, axis=2)
# Calculate reverberation M and general factor npfct
Ms = 1 - Rp * Rm * np.exp(-2 * iGam * ds)
npfct = factAng * zetaH[:, lsrc] / (fact * off * lgam * Ms)
return Rp, Rm, npfct
# TE modes TE[uu, ud, du, dd]
Rp, Rm, npfct = get_rp_rm(zetaH)
PTE[0] += npfct * Rp * Rm * np.exp(-lgam * (2 * ds - zrec + zsrc))
PTE[1] += npfct * Rp * np.exp(-lgam * (2 * ddepth[lrec + 1] - zrec - zsrc))
PTE[2] += npfct * Rm * np.exp(-lgam * (zrec + zsrc))
PTE[3] += npfct * Rp * Rm * np.exp(-lgam * (2 * ds + zrec - zsrc))
# TM modes TM[uu, ud, du, dd]
Rp, Rm, npfct = get_rp_rm(etaH)
PTM[0] -= npfct * Rp * Rm * np.exp(-lgam * (2 * ds - zrec + zsrc))
PTM[1] += npfct * Rp * np.exp(-lgam * (2 * ddepth[lrec + 1] - zrec - zsrc))
PTM[2] += npfct * Rm * np.exp(-lgam * (zrec + zsrc))
PTM[3] -= npfct * Rp * Rm * np.exp(-lgam * (2 * ds + zrec - zsrc))
# 3.5 Reshape for number of sources
for i, val in enumerate(PTE):
PTE[i] = np.squeeze(val.reshape((-1, nrec, nsrc), order='F'))
for i, val in enumerate(PTM):
PTM[i] = np.squeeze(val.reshape((-1, nrec, nsrc), order='F'))
# === 4. FINISHED ============
printstartfinish(verb, t0)
# return [TMuu, TMud, TMdu, TMdd, TMdf], [TEuu, TEud, TEdu, TEdd, TEdf]
return PTM, PTE
def test_strvar():
out = utils._strvar(np.arange(3) * np.pi)
assert out == "0 3.14159 6.28319"
out = utils._strvar(np.pi, '{:20.10e}')
assert out == " 3.1415926536e+00"
