Why zero values in matrix

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Milan
Milan 2022-10-30
评论： Stephen23 2022-10-30
Ran in:
%hello, here eventhough matrix components are not zero, I am getting zero values when I put A a very large number. %Is there any way to avoid such?
E = 1;
I_z = 1;
%E_Iz = E*I_z;
R = 1;
L = R; %R
%A = 1;
A = 10^9; %so that axial strain is very small
% K1 = A*E/L;
% K2 = 12*E*I_z/L^3;
% K3= 6*E*I_z/L^2;
% K4 = 4*E*I_z/L;
% K5 = 2*E*I_z/L;
% for element 1
Ke_1_local = [A*E/L 0 0 -A*E/L 0 0;
0 12*E*I_z/L^3 6*E*I_z/L^2 0 -12*E*I_z/L^3 6*E*I_z/L^2;
0 6*E*I_z/L^2 4*E*I_z/L 0 -6*E*I_z/L^2 2*E*I_z/L;
-A*E/L 0 0 A*E/L 0 0;
0 -12*E*I_z/L^3 -6*E*I_z/L^2 0 12*E*I_z/L^3 -6*E*I_z/L^2;
0 6*E*I_z/L^2 2*E*I_z/L 0 -6*E*I_z/L^2 4*E*I_z/L ]
Ke_1_local = 6×6
1.0e+09 * 1.0000 0 0 -1.0000 0 0 0 0.0000 0.0000 0 -0.0000 0.0000 0 0.0000 0.0000 0 -0.0000 0.0000 -1.0000 0 0 1.0000 0 0 0 -0.0000 -0.0000 0 0.0000 -0.0000 0 0.0000 0.0000 0 -0.0000 0.0000

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Walter Roberson
Walter Roberson 2022-10-30
编辑：Walter Roberson 2022-10-30
you overlooked the 1.0e+09 * at the top of the display. Those 0.0000 are not true zeros, they are 1.0e+09 * a number that is 0.0000 to four decimal places.
I suggest that you give the command
format long g
and then ask to display the matrix
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Milan
Milan 2022-10-30
I see, I tried it and it worked, thanks for your help!
Stephen23
Stephen23 2022-10-30
"I mean for example value at 2, 2 is zero right..."
No, it is not. If the value is exactly zero then MATLAB displays it as "0". The trailing zero digits of "0.0000" tell us that value is not exactly zero, but that the trailing digits are zero when displayed with four digits after the decimal point.

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