Inner matrix dimensions must agree

%ben newton swansea university 956205

k = 997.584; %stiffness, units = N/m

m = 10.692; %mass, units = kg

xo = 0.026844; %initial displacement, units = m

vo = 0:0.001:5; %initial velocity, units = m/s

t = 0.735; %time, units = s

x = 0.0852; %dispacement, units = m

c = 36.84; %damping coefficient, units = kg/s

wn = sqrt(k/m); %natural frequency, units = rad/s

ccrit = 2*sqrt(k*m); %critical damping coefficient, units = kg/s

zeta = c/ccrit; %damping ratio, no units

wd = wn*sqrt(1 - zeta^2); %damped natural frequency, units = rad/s

A = sqrt((vo+zeta*wn*xo).^2 + (xo*wd)^2/wd^2);

phi = atan((xo*wd)./vo+zeta*wn*xo); %phase angle, units = radians

x@time = A.*exp(-zeta.*wn.*t)*sin((wd.*t)+phi);

%everythings fine up until the last line, gives the error using * inner matrix dimensions must agree

all matrices used are the same shape an size etc and .* has been used

but i still get the error message

please help

[Guillaume]

This question should not be deleted. This is a public forum not your personal support service. The price you pay for getting help is that your question can be used by others with the same problem.

Your question has been flagged so that Mathworks can restore it. They usually do.

[Stephen23]

Original question:

%ben newton swansea university 956205
k = 997.584; %stiffness, units = N/m 
m = 10.692; %mass, units = kg 
xo = 0.026844; %initial displacement, units = m 
vo = 0:0.001:5; %initial velocity, units = m/s
t = 0.735; %time, units = s 
x = 0.0852; %dispacement, units = m 
c = 36.84; %damping coefficient, units = kg/s
wn = sqrt(k/m); %natural frequency, units = rad/s
ccrit = 2*sqrt(k*m); %critical damping coefficient, units = kg/s 
zeta = c/ccrit; %damping ratio, no units 
wd = wn*sqrt(1 - zeta^2); %damped natural frequency, units = rad/s
A = sqrt((vo+zeta*wn*xo).^2 + (xo*wd)^2/wd^2); 
phi = atan((xo*wd)./vo+zeta*wn*xo); %phase angle, units = radians 
x@time = A.*exp(-zeta.*wn.*t)*sin((wd.*t)+phi);
%everythings fine up until the last line, gives the error using * inner matrix dimensions must agree 

all matrices used are the same shape an size etc and .* has been used

but i still get the error message

please help

[Rena Berman]

(Answers Dev) Restored edit

Answer 1

[Katie]

You're missing a dot in front of the * in front of the sin

x_time = A.*exp(-zeta.*wn.*t).*sin((wd.*t)+phi);