Thread Subject:

Error using times, Matrix dimensions must agree

Dear friends,

Have a good day,

i am getting this message "Error using times, MD must agree",
here are my three lines of code;

t=linspace(0,.0000001,200)
z=linspace(-.0002,.0002,200);
Initial_value=(exp(-(z.^2)./L.^2).*cos(z))./z;
E_1=vee_1*(Y(:,3).*t)+initial_value.*(z- vee_1*t);%------this is where the error comes

Y(:,3) is of size 200x1;


i dont know why this error comes, as i have checked the syntax and logic, it seems correct to me, yet its giving this error.

your help is greatly appreciated.

thanks alot

"salman " <salmanabdullah9@gmail.com> wrote in message <iqsrio$kfj$1@newscl01ah.mathworks.com>...
>
> Dear friends,
>
> Have a good day,
>
> i am getting this message "Error using times, MD must agree",
> here are my three lines of code;
>
> t=linspace(0,.0000001,200)
> z=linspace(-.0002,.0002,200);
> Initial_value=(exp(-(z.^2)./L.^2).*cos(z))./z;
> E_1=vee_1*(Y(:,3).*t)+initial_value.*(z- vee_1*t);%------this is where the error comes
>
> Y(:,3) is of size 200x1;
>
>
> i dont know why this error comes, as i have checked the syntax and logic, it seems correct to me, yet its giving this error.
>
> your help is greatly appreciated.
>
> thanks alot
- - - - - - - -
  The multiplication in "(Y(:,3).*t)" is invalid since Y(:,3) is a column vector and t is a row vector. They must be the same size to use ".*". Also you should make sure that "vee_1" is a scalar or you will have other troubles.

Roger Stafford

"Roger Stafford" wrote in message <iqssvn$ob1$1@newscl01ah.mathworks.com>...
> "salman " <salmanabdullah9@gmail.com> wrote in message <iqsrio$kfj$1@newscl01ah.mathworks.com>...
> >
> > Dear friends,
> >
> > Have a good day,
> >
> > i am getting this message "Error using times, MD must agree",
> > here are my three lines of code;
> >
> > t=linspace(0,.0000001,200)
> > z=linspace(-.0002,.0002,200);
> > Initial_value=(exp(-(z.^2)./L.^2).*cos(z))./z;
> > E_1=vee_1*(Y(:,3).*t)+initial_value.*(z- vee_1*t);%------this is where the error comes
> >
> > Y(:,3) is of size 200x1;
> >
> >
> > i dont know why this error comes, as i have checked the syntax and logic, it seems correct to me, yet its giving this error.
> >
> > your help is greatly appreciated.
> >
> > thanks alot
> - - - - - - - -
> The multiplication in "(Y(:,3).*t)" is invalid since Y(:,3) is a column vector and t is a row vector. They must be the same size to use ".*". Also you should make sure that "vee_1" is a scalar or you will have other troubles.
>
> Roger Stafford

Dear Roger,

if i change the above equation and replace Y(:,3) by [Y(:,3)]', so now this becomes and row vector. after this however, the previous error is gone, but now i want to create the mesh from t and z and then get surface plot for E(z,t). but it says

Warning: Matrix dimensions must agree, not rendering mesh.

i used this one;

E_1=vee_1*((Y(:,3))'.*t)+Initial_value.*(z- t);
meshgrid(t,z);
surf(t,z,E_1)

where;

size(z)=1 200
size(t)=1 200
size(Y(:,3)')=1 200
size(Initial_value)=1 200,

i will be grateful for help.

thanks

On May 16, 11:55 pm, "salman " <salmanabdull...@gmail.com> wrote:
> Dear friends,
>
> Have a good day,
>
> i am getting this message "Error using times, MD must agree",
> here are my three lines of code;
>
> t=linspace(0,.0000001,200)
> z=linspace(-.0002,.0002,200);
> Initial_value=(exp(-(z.^2)./L.^2).*cos(z))./z;
> E_1=vee_1*(Y(:,3).*t)+initial_value.*(z- vee_1*t);%------this is where the error comes
>
> Y(:,3) is of size 200x1;
>
> i dont know why this error comes, as i have checked the syntax and logic, it seems
> correct to me, yet its giving this error.

"seems" is not good enough ...
check the matrix sizes before multiplication

help size
doc size

Hope this helps.

Greg