e2ecdcfe33
Former-commit-id:a02aeb236c[formerly9f19e3f712] [formerlya02aeb236c[formerly9f19e3f712] [formerly06a8b51d6d[formerly 64fa9254b946eae7e61bbc3f513b7c3696c4f54f]]] Former-commit-id:06a8b51d6dFormer-commit-id:8e80217e59[formerly3360eb6c5f] Former-commit-id:377dcd10b9
103 lines
3.4 KiB
Python
103 lines
3.4 KiB
Python
##
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# This software was developed and / or modified by Raytheon Company,
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# pursuant to Contract DG133W-05-CQ-1067 with the US Government.
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#
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# U.S. EXPORT CONTROLLED TECHNICAL DATA
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# This software product contains export-restricted data whose
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# export/transfer/disclosure is restricted by U.S. law. Dissemination
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# to non-U.S. persons whether in the United States or abroad requires
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# an export license or other authorization.
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#
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# Contractor Name: Raytheon Company
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# Contractor Address: 6825 Pine Street, Suite 340
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# Mail Stop B8
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# Omaha, NE 68106
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# 402.291.0100
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#
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# See the AWIPS II Master Rights File ("Master Rights File.pdf") for
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# further licensing information.
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###
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from numpy import empty, isscalar, shape, NaN
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##
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# Calculate the divergence of Vector.
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# Because of the way in which this is calculated, the outermost
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# row and column of the output array is always invalid.
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#
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# @change: quan parm added 2008/06/23 wldougher
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#
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# @param Vector: 2-tuple (U,V) of arrays of values
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# @param dx: 2D array of spacing between grid points
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# @param dy: 2D array of spacing between grid points
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# @param quan: Quantity parameter (optional; defaults to constant 1)
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# @return: divergence
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def execute(vec, dx, dy, quan=1.0):
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"""Calculate the divergence of Vector from dx and dy.\n\
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for each output cell, \n
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u = Vector[0] \n
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v = Vector[1] \n
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diff_u = u[i+1,j]*q[i+1,j] - u[i-1,j]*q[i-1,j] \n
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diff_v = u[i,j+1]*q[i,j+1] - u[i,j-1]*q[i,j-1] \n
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dudx = diff_u/dx[i,j] \n
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dvdy = diff_v/dy[i,j] \n
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diverg[i,j] = (dudx + dvdy)/2 \n
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"""
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vec_U = vec[2]
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vec_V = vec[3]
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vshape = shape(vec_U)
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if len(vshape) < 2:
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raise TypeError, "Divergence: Vector must be at least 2-D."
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if vshape[0] < 3:
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raise ValueError, "Divergence: Vector's first dimension must be at least 3."
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if vshape[1] < 3:
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raise ValueError, "Divergence: Vector's second dimension must be at least 3."
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rslt = empty(vshape, dtype=vec_U.dtype)
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rslt[0,:] = NaN
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rslt[-1,:] = NaN
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rslt[1:-1, 0] = NaN
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rslt[1:-1, -1] = NaN
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if shape(quan) == ():
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quan_rl = quan
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quan_tb = quan
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else:
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quan_rl = quan[1:-1]
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quan_tb = quan[:,1:-1]
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QU = quan_rl * vec_U[1:-1,:]
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QV = quan_tb * vec_V[:,1:-1]
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diff_U = QU[:,2:] - QU[:,0:-2]
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diff_V = QV[0:-2,:] - QV[2:,:]
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# if dx is a constant or one-element array, just divide by it.
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# otherwise, divide each cell in diff_U by the corresponding cell in dx.
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dxshape = shape(dx)
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ldxs = len(dxshape)
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if ldxs == 0 or sum(dxshape)==ldxs:
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dudx = diff_U/dx
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elif dxshape==vshape:
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dudx = diff_U/dx[1:-1,1:-1]
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else:
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raise TypeError, "Divergence: dx must be a scalar or the same shape as Vector."
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# if dy is a constant or one-element array, just divide by it.
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# otherwise, divide each cell in diff_V by the corresponding cell in dy.
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dyshape = shape(dy)
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ldys = len(dyshape)
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if ldys == 0 or sum(dyshape)==ldys:
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dvdy = diff_V/dy
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elif dyshape==vshape:
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dvdy = diff_V/dy[1:-1,1:-1]
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else:
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raise TypeError, "Divergence: dy must be a scalar or the same shape as Vector."
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rslt[1:-1,1:-1] = (dudx + dvdy)/2
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return rslt
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