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74 lines
2.2 KiB
Python
74 lines
2.2 KiB
Python
"""
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Basic code snippets for opencl FDTD
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"""
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from typing import List
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import numpy
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def shape_source(shape: List[int] or numpy.ndarray) -> str:
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"""
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Defines sx, sy, sz C constants specifying the shape of the grid in each of the 3 dimensions.
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:param shape: [sx, sy, sz] values.
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:return: String containing C source.
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"""
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sxyz = """
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// Field sizes
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const int sx = {shape[0]};
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const int sy = {shape[1]};
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const int sz = {shape[2]};
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""".format(shape=shape)
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return sxyz
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# Defines dix, diy, diz constants used for stepping in the x, y, z directions in a linear array
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# (ie, given Ex[i] referring to position (x, y, z), Ex[i+diy] will refer to position (x, y+1, z))
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dixyz_source = """
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// Convert offset in field xyz to linear index offset
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const int dix = sz * sy;
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const int diy = sz;
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const int diz = 1;
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"""
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# Given a linear index i and shape sx, sy, sz, defines x, y, and z
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# as the 3D indices of the current element (i).
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xyz_source = """
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// Convert linear index to field index (xyz)
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const int x = i / (sz * sy);
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const int y = (i - x * sz * sy) / sz;
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const int z = (i - y * sz - x * sz * sy);
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"""
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# Source code for updating the E field; maxes use of dixyz_source.
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maxwell_E_source = """
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// E update equations
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Ex[i] += dt / epsx[i] * ((Hz[i] - Hz[i-diy]) - (Hy[i] - Hy[i-diz]));
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Ey[i] += dt / epsy[i] * ((Hx[i] - Hx[i-diz]) - (Hz[i] - Hz[i-dix]));
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Ez[i] += dt / epsz[i] * ((Hy[i] - Hy[i-dix]) - (Hx[i] - Hx[i-diy]));
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"""
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# Source code for updating the H field; maxes use of dixyz_source and assumes mu=0
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maxwell_H_source = """
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// H update equations
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Hx[i] -= dt * ((Ez[i+diy] - Ez[i]) - (Ey[i+diz] - Ey[i]));
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Hy[i] -= dt * ((Ex[i+diz] - Ex[i]) - (Ez[i+dix] - Ez[i]));
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Hz[i] -= dt * ((Ey[i+dix] - Ey[i]) - (Ex[i+diy] - Ex[i]));
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"""
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def type_to_C(float_type: numpy.float32 or numpy.float64) -> str:
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"""
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Returns a string corresponding to the C equivalent of a numpy type.
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Only works for float32 and float64.
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:param float_type: numpy.float32 or numpy.float64
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:return: string containing the corresponding C type (eg. 'double')
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"""
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if float_type == numpy.float32:
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arg_type = 'float'
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elif float_type == numpy.float64:
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arg_type = 'double'
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else:
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raise Exception('Unsupported type')
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return arg_type
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