28 lines
728 B
Mathematica
28 lines
728 B
Mathematica
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function B = MatrixB( ie )
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% <EFBFBD><EFBFBD><EFBFBD>㵥Ԫ<EFBFBD><EFBFBD>Ӧ<EFBFBD><EFBFBD><EFBFBD><EFBFBD><EFBFBD><EFBFBD>B
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% <EFBFBD><EFBFBD><EFBFBD><EFBFBD><EFBFBD><EFBFBD><EFBFBD><EFBFBD>:
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% ie ---- <EFBFBD><EFBFBD>Ԫ<EFBFBD><EFBFBD>
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% <EFBFBD><EFBFBD><EFBFBD><EFBFBD>ֵ:
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% B ---- <EFBFBD><EFBFBD>ԪӦ<EFBFBD><EFBFBD><EFBFBD><EFBFBD><EFBFBD><EFBFBD>
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global gNode gElement
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xi = gNode( gElement( ie, 1 ), 1 ) ;
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yi = gNode( gElement( ie, 1 ), 2 ) ;
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xj = gNode( gElement( ie, 2 ), 1 ) ;
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yj = gNode( gElement( ie, 2 ), 2 ) ;
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xm = gNode( gElement( ie, 3 ), 1 ) ;
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ym = gNode( gElement( ie, 3 ), 2 ) ;
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ai = xj*ym - xm*yj ;
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aj = xm*yi - xi*ym ;
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am = xi*yj - xj*yi ;
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bi = yj - ym ;
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bj = ym - yi ;
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bm = yi - yj ;
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ci = -(xj-xm) ;
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cj = -(xm-xi) ;
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cm = -(xi-xj) ;
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area = abs((ai+aj+am)/2) ;
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B = [bi 0 bj 0 bm 0
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0 ci 0 cj 0 cm
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ci bi cj bj cm bm] ;
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B = B/2/area ;
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return
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