Source code for magpylib._lib.classes.moments

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# magpylib -- A Python 3 toolbox for working with magnetic fields.
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#               Michael Ortner <>
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from numpy import array, float64, ndarray, ones, tile, shape
from magpylib._lib.mathLib import angleAxisRotation_priv
from magpylib._lib.classes.base import MagMoment
from magpylib._lib.fields.Moment_Dipole import Bfield_Dipole
from magpylib._lib.fields.Moment_Dipole_vector import Bfield_DipoleV
from magpylib._lib.mathLib_vector import angleAxisRotationV_priv

# tool-tip / intellisense helpers ---------------------------------------------
# Class initialization is done purely by kwargs. While some # of these can be 
# set to zero by default other MUST be given to make any sense 
# (e.g. magnetization). To improve tool tips and intellisense we inizilize them
# with names, e.g. mag=(Mx, My, Mz). This looks good, but it requires that
# these names are pre-initialzed:
Mx = My = Mz = 0.0

# -------------------------------------------------------------------------------
[docs]class Dipole(MagMoment): """ This class represents a magnetic dipole. The dipole is constructed such that its moment :math:`|M|` is given in :math:`[mT*mm^3]` and corresponds to the moment of a cuboid magnet with remanence field Br and Volume V such that :math:`|M| = Br*V`. Scalar input is either integer or float. Vector input format can be either list, tuple or array of any data type (float, int). Parameters ---------- moment : vec3 [mT] Set magnetic dipole moment in units of [mT*mm^3]. pos=[0,0,0] : vec3 [mm] Set position of the moment in units of [mm]. angle=0.0 : scalar [deg] Set angle of orientation of the moment in units of [deg]. axis=[0,0,1] : vec3 [] Set axis of orientation of the moment. Attributes ---------- moment : arr3 [mT] Magnetic dipole moment in units of [mT*mm^3] (:math:`|moment| = Br*V` of a cuboid magnet.) position : arr3 [mm] Position of the moment in units of [mm]. angle : float [deg] Angle of orientation of the moment in units of [deg]. axis : arr3 [] Axis of orientation of the moment. Examples -------- >>> magpylib as magpy >>> mom = magpy.source.moment.Dipole(moment=[0,0,1000]) >>> B = mom.getB([1,0,1]) >>> print(B) [0.33761862 0. 0.11253954] Note ---- The following Methods are available to all source objects. """
[docs] def getB(self, pos): # Particular Line current B field calculation. Check RCS for getB() interface # vectorized code if input is an Nx3 array if type(pos) == ndarray: if len(shape(pos))==2: # list of positions - use vectorized code # vector size NN = shape(pos)[0] # prepare vector inputs POSREL = pos - self.position ANG = ones(NN)*self.angle AX = tile(self.axis,(NN,1)) MOM = tile(self.moment,(NN,1)) # compute rotations and field ROTATEDPOS = angleAxisRotationV_priv(ANG, -AX, POSREL) BB = Bfield_DipoleV(MOM,ROTATEDPOS) BCM = angleAxisRotationV_priv(ANG, AX, BB) return BCM # secure input type and check input format p1 = array(pos, dtype=float64, copy=False) # relative position between mag and obs posRel = p1 - self.position # rotate this vector into the CS of the magnet (inverse rotation) rotatedPos = angleAxisRotation_priv(self.angle, -self.axis, posRel) # pylint: disable=invalid-unary-operand-type # rotate field vector back BCm = angleAxisRotation_priv(self.angle, self.axis, Bfield_Dipole(self.moment, rotatedPos)) # BCm is the obtained magnetic field in Cm # the field is well known in the magnet coordinates. return BCm
def __repr__(self): """ This is for the IPython Console When you call a defined dipole, this method shows you all its components. Examples -------- >>> from magpylib import source >>> d = source.moment.Dipole([1.0,2.0,3.0], [3.0,2.0,1.0]) >>> d name: Dipole moment: x: 1.0mT, y: 2.0mT, z: 3.0mT position: x: 3.0mm, y: 2.0mm, z:1.0mm angle: 0.0 Degrees axis: x: 0.0, y: 0.0, z: 1.0 """ return "type: {} \n moment: x: {}, y: {}, z: {} \n position: x: {}, y: {}, z:{} \n angle: {} \n axis: x: {}, y: {}, z: {}".format("moments.Dipole", *self.moment, *self.position, self.angle, *self.axis)