# Inner matrix must agree

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Alejandro Urbina on 23 Feb 2016
Commented: Moe_2015 on 23 Feb 2016
So im trying to run the following code...
A1=4; A2=-2; B1=3; B2=1; tau1=100*10^-3; tau2=20*10^-3; w=40*pi; x = linspace(0,2*pi,100); y1 = (A1*exp(-x/tau1))+(A2*exp(-x/tau2)); y2 = (A1*exp(-x/tau1))+(A2*(x/tau1)*exp(-x/tau1)); y3 = (exp(-x/tau1)*(B1*cos(w*x)+B2*sin(w*x))); figure plot(x,y1,'--',x,y2,':',x,y3,'r')
I get the following error:
Error using * Inner matrix dimensions must agree.
Error in Urbina_ps1 (line 10) y2 = (A1*exp(-x/tau1))+(A2*(x/tau1)*exp(-x/tau1));
I dont know how to solve the matrix problem that is happening in the sencond termn of the equation... Im new to matlab and i have been looking for tutorials to trying to solve this...
Ill appreciate any help thank you

Moe_2015 on 23 Feb 2016
Edited: Moe_2015 on 23 Feb 2016
It's because of the x variable. Your x variable is a row vector of a 100 elements. When you use "*" by itself it is doing matrix multiplication. Thus, throughout your code you are trying to multiply a 1X100 vector with another 1X100 vector which is not possible. You should replace all "*" with ".*" as this will allow you to do element wise multiplication.
Alejandro Urbina on 23 Feb 2016
thank you Moe_2015!!!
Moe_2015 on 23 Feb 2016
You are welcome. If this helped you with your problem please accept the answer for the benefit of others.