


GETJACOBIAN - computes the jacobian for a triaelem
Usage:
J=GetJacobian(triaelem,xyz_list,gauss_coord)
See also GETJACOBIANDETERMINANT, GETJACOBIANINVERT

0001 function J=GetJacobian(triaelem,xyz_list,gauss_l1l2l3) 0002 %GETJACOBIAN - computes the jacobian for a triaelem 0003 % 0004 % Usage: 0005 % J=GetJacobian(triaelem,xyz_list,gauss_coord) 0006 % 0007 % See also GETJACOBIANDETERMINANT, GETJACOBIANINVERT 0008 0009 %The Jacobian is constant over the element, discard the gaussian points. 0010 0011 %Non optimized version 0012 %J=zeros(2,2); 0013 % 0014 %x1=xyz_list(1,1); 0015 %y1=xyz_list(1,2); 0016 %x2=xyz_list(2,1); 0017 %y2=xyz_list(2,2); 0018 %x3=xyz_list(3,1); 0019 %y3=xyz_list(3,2); 0020 % 0021 %J(1,1)=1.0/2.0*(x2-x1); 0022 %J(1,2)=sqrt(3.0)/6.0*(2*x3-x1-x2); 0023 %J(2,1)=1.0/2.0*(y2-y1); 0024 %J(2,2)=sqrt(3.0)/6.0*(2*y3-y1-y2); 0025 0026 0027 %Same code, a little optimized 0028 J=[ 1.0/2.0*(xyz_list(2,1)-xyz_list(1,1)) sqrt(3.0)/6.0*(2*xyz_list(3,1)-xyz_list(1,1)-xyz_list(2,1)) 0029 1.0/2.0*(xyz_list(2,2)-xyz_list(1,2)) sqrt(3.0)/6.0*(2*xyz_list(3,2)-xyz_list(1,2)-xyz_list(2,2))]; 0030 0031