Error using * Inner matrix dimensions must agree.

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Valeria Garcia 2014-10-2

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此问题的直接链接

https://ww2.mathworks.cn/matlabcentral/answers/157153-error-using-inner-matrix-dimensions-must-agree

评论： Star Strider 2014-10-2

Okay so I' trying put in the following commands.

%Constants%
hbar = 1.055e-34;   %J s  
c = 2.998e8;        %m/s    Speed of light
eps = 8.854e-12;     %C^2/N/m^2  permitivity of free space
%system parameters%
W = 20e-6;          %m          Beam width
l = 300e-6;         %m          Beam length
h = 2e-6;           %m          Beam thickness
rho = 2.33e3;       %kg/m^3             Material density (silicon)
E = 169e9;          %Pa         Youngs modulous
g = 8e-6;           %m          Initial gap distance
Q = 350             %Quality factor
V = 16;              %V          AC peak voltage
A = W*h;            %m^2        Cross sectional area
I = W*h*h*h/12;     %m^4        Cross sectional intertia
wn = 3.51562; %s^-1       natural frequency
%%%Constants from modeshapes%%%
g011 = 0.7830;     % g011 = <1,phi_1>      
g111 = 1;           % g111 = <phi_1,phi_1> 
g211 = 1.4778;     % g211 = <phi_1^2, phi_1>
g311 = 2.3488;      % g311 = <phi_1^3, phi_1>
%This constant tracks effects of Casimer Effect
%alpha = (pi*pi*hbar*c*W*l^4)/(240*g^5*E*I); 
alpha = 0;
%This constant tracks effects of the Electrostatic Force
%delta =(eps*W*l^4)/(2*g^3*E*I)*V*V;
delta = .01;
%This constant tracks effects of Fringing Correction to Elec. Force
%f = 0.65*g/W;
f = 0.26;
%Dimensionless damping coeff.
%b0*l^2/g*sqrt(1/(rho*A*E*I));
%b = wn/Q
b = 0.001; 
C1 = delta*(1+f)/2;
C2 = delta*(2+f)/2;
C3 = delta*(3+f)/2;
C4 = delta*(4+f)/2;
gamma=0.001:0.0001:pi;
amp = 2.*g111.*wn.*b./C3./g211./sin(gamma)-sqrt((2.*g111.*wn.*b./C3./g211./sin(gamma)).^2 - 4.*C1.*g011./C3./g211);

Where exactly should I put the periods so I don't get that error.

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Nalini Vishnoi 2014-10-2

编辑：Nalini Vishnoi 2014-10-2

Please specify what are the values for b, alpha, delta, wn, g111 .

Valeria Garcia 2014-10-2

oops! should have explained more. I already put them.

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Answer 1

Star Strider 2014-10-2

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此回答的直接链接

https://ww2.mathworks.cn/matlabcentral/answers/157153-error-using-inner-matrix-dimensions-must-agree#answer_153680

We know gamma is a vector, but nothing about whether the other variables are vectors or scalars. In the absence of that information, just vectorise the entire expression unless you know specific operations involve only scalars.

Also, highlighting your code and then using the [{}Code] button makes it easier to read.