Matrix display wrong value
显示 更早的评论
clear all
clc
% This is Tutorial Q1 Very important make sure the parameters are correct
L1=1000;
L2=2000;
b1=10;
h1=10;
b2=20;
h2=20;
A1=b1*h1;
A2=b2*h2;
E1=70e3;
E2=205e3;
c1=cos(deg2rad(0));
s1=sin(deg2rad(0));
c2=cos(deg2rad(-90));
s2=sin(deg2rad(-90));
I1=b1*h1^3/12;
I2=b2*h2^3/12;
k1 = [ A1*E1/L1 0 0 -A1*E1/L1 0 0; ...
0 12*E1*I1/L1^3 6*E1*I1/L1^2 0 -12*E1*I1/L1^3 6*E1*I1/L1^2; ...
0 6*E1*I1/L1^2 4*E1*I1/L1 0 -6*E1*I1/L1^2 2*E1*I1/L1; ...
-A1*E1/L1 0 0 A1*E1/L1 0 0; ...
0 -12*E1*I1/L1^3 -6*E1*I1/L1^2 0 (12*E1*I1)/L1^3 -6*E1*I1/L1^2; ...
0 6*E1*I1/L1^2 2*E1*I1/L1 0 -6*E1*I1/L1^2 4*E1*I1/L1]
k2 = [ A2*E2/L2 0 0 -A2*E2/L2 0 0; ...
0 12*E2*I2/L2^3 6*E2*I2/L2^2 0 -12*E2*I2/L2^3 6*E2*I2/L2^2; ...
0 6*E2*I2/L2^2 4*E2*I2/L2 0 -6*E2*I2/L2^2 2*E2*I2/L2; ...
-A2*E2/L2 0 0 A2*E2/L2 0 0; ...
0 -12*E2*I2/L2^3 -6*E2*I2/L2^2 0 12*E2*I2/L2^3 -6*E2*I2/L2^2; ...
0 6*E2*I2/L2^2 2*E2*I2/L2 0 -6*E2*I2/L2^2 4*E2*I2/L2]
lamd1 = [c1 s1 0 0 0 0; ...
-s1 c1 0 0 0 0; ...
0 0 1 0 0 0; ...
0 0 0 c1 s1 0; ...
0 0 0 -s1 c1 0; ...
0 0 0 0 0 1];
lamd2 = [c2 s2 0 0 0 0; ...
-s2 c2 0 0 0 0; ...
0 0 1 0 0 0; ...
0 0 0 c2 s2 0; ...
0 0 0 -s2 c2 0; ...
0 0 0 0 0 1];
K1 = lamd1'*k1*lamd1; % 1 1 1 2 2 2
K2 = lamd2'*k2*lamd2;% 2 2 2 3 3 3
Kg=zeros(9,9);
Kg(1:6,1:6) = K1;
Kg(4:9,4:9) = Kg(4:9,4:9)+K2;
Kgm = Kg;
% Loading condition[ r1x r1y r1th 2000 3000 -500 r3x r3y r3th]
%
F = [ 0 0 0 2000 3000 -500 0 0 0]'
% boundary conditions F [u1 v1 th1 u2 v2 th2 u3 v3 th3 ]
% u1 v1 th1 u3 v3 th3 = 0
%Modify Kg
Kg = Kg(4:6,4:6);
Fg = [2000 3000 -500]'
U1 = Kg\Fg; % u2 v2 th2
y1 = 5*10^-3;
x1 = 0;
B1 = [-1/L1 -y1*(12*x1-6*L1)/L1^3 -y1*(6*x1-4*L1)/L1^2 1/L1 y1*(12*x1-6*L1)/L1^3 ...
-y1*(6*x1-2*L1)/L1^2 ]
Exx1= B1*lamd1*[ 0 0 0 U1(1) U1(2) U1(3)]'
sig1 = E1 *Exx1
Need help on why matrix is displaying 0 on some arrays when it is not , for example on the attached screen shot, Kg(2,2) is 0,7 but matlab displays as 0
1 个评论
As you can see, there is a scaling factor at the start of the result. There you can see that you need to multiply each element by 1e5, meaning that 0.7 is rounded to 0e5 in the display.
If you want more control over how values are shown, you show read the documentation for the format function. It that is not enough, you will need to use fprintf.
采纳的回答
L1=1000;
L2=2000;
b1=10;
h1=10;
b2=20;
h2=20;
A1=b1*h1;
A2=b2*h2;
E1=70e3;
E2=205e3;
c1=cos(deg2rad(0));
s1=sin(deg2rad(0));
c2=cos(deg2rad(-90));
s2=sin(deg2rad(-90));
I1=b1*h1^3/12;
I2=b2*h2^3/12;
k1 = vpa([ A1*E1/L1 0 0 -A1*E1/L1 0 0; ...
0 12*E1*I1/L1^3 6*E1*I1/L1^2 0 -12*E1*I1/L1^3 6*E1*I1/L1^2; ...
0 6*E1*I1/L1^2 4*E1*I1/L1 0 -6*E1*I1/L1^2 2*E1*I1/L1; ...
-A1*E1/L1 0 0 A1*E1/L1 0 0; ...
0 -12*E1*I1/L1^3 -6*E1*I1/L1^2 0 (12*E1*I1)/L1^3 -6*E1*I1/L1^2; ...
0 6*E1*I1/L1^2 2*E1*I1/L1 0 -6*E1*I1/L1^2 4*E1*I1/L1],4)
k2 = vpa([ A2*E2/L2 0 0 -A2*E2/L2 0 0; ...
0 12*E2*I2/L2^3 6*E2*I2/L2^2 0 -12*E2*I2/L2^3 6*E2*I2/L2^2; ...
0 6*E2*I2/L2^2 4*E2*I2/L2 0 -6*E2*I2/L2^2 2*E2*I2/L2; ...
-A2*E2/L2 0 0 A2*E2/L2 0 0; ...
0 -12*E2*I2/L2^3 -6*E2*I2/L2^2 0 12*E2*I2/L2^3 -6*E2*I2/L2^2; ...
0 6*E2*I2/L2^2 2*E2*I2/L2 0 -6*E2*I2/L2^2 4*E2*I2/L2],4)
1 个评论
VBBV
2023-6-7
Use vpa with desired decimal places for those matrices
更多回答（0 个）
类别
在 帮助中心 和 File Exchange 中查找有关 Conversion Between Symbolic and Numeric 的更多信息
Translated by 
