number to variables in matrix

Dear all,

How can I apply below numbers to the specific matrix defined with respect to variable?

For example,

U=[x , 2*x];

And, we want to apply below numbers which are in matrix form:

X1=[0 1];
X2=[2 3];

Thanks

Answer 1

[Star Strider]

I am not certain I understand what you want to do, so here are two possibilities, both using anonymous functions:

The first treats ‘x’ as a discrete single argument:

U1= @(x) [x , 2*x];         % Vector ‘x’

X1=[0 1]; 
X2=[2 3];

U1X1 = U1(X1)
U1X2 = U1(X2)

producing:

U1X1 =

       0     1    0    2

U1X2 =

       2     3    4    6

The second uses each element of ‘x’ separately:

U2 = @(x)  [x(1) , 2*x(2)]; % Separate Elements of ‘x’

U2X1 = U2(X1)
U2X2 = U2(X2)

producing:

U2X1 =

       0     2

U2X2 =

       2     6

[TT]

Thank you,

However, please note that the function (with respect to 'x') is not defined such that I wrote. I mean U is obtained by writing a long code and it is not same for different number of elements. For instance, it might be like this U=[x,x^2,x^3,x^4], and X1,X2,X3,X4 regarding the code is another variable.

thank you again!

[Star Strider]

My pleasure!

First, is ‘U1’ or ‘U2’ the format you intend? I need to know that before I proceed. I still don’t know if by ‘x’ you mean the entire vector for each ‘x’ in ‘U’ or the individual elements of ‘x’ for each element of ‘U’.

The ‘U’ function will likely be easy to write once we get this sorted.

[TT]

Here is the code:

ne=input('enter number of elements: ');

n=input('enter number of nodes: ');

L=input('enter the range: ')

le=L/ne

%Node point coordinates

e=1

X1(e:1:ne)=[0:le:L-le]

X2(e:1:ne)=[0+le:le:L]

%Shape functions

syms x

for i=1:ne

N1(i)=(X2(i)-x)/le;

N2(i)=(x-X1(i))/le;

end

N1

N2 % Interpolation displacement

d1=X1.^3

d2=X2.^3

% Define displacement in terms of shape functions

for i=1:ne

    U(i)=N1(i)*d1(i)+N2(i)*d2(i);

end

U

for example, L=1, ne =2 ,n=3(should be 1+ne)! as you see we obtain 'U'. Now I want to continue the code by applying the first column of each X1,X2 to U(1) and second column of each X1,X2 to U(2).

And, generalize this to more number of elements!

thank you!

[Star Strider]

I am completely lost.

It seems to me that is exactly what you are doing, although indirectly, since ‘N1’, ‘d1’, ‘N2’ and ‘d2’ are all functions of the respective elements of ‘X1’ and ‘X2’.

[TT]

Why?!

I obtain U as function of x but in matrix. Now, I just want to apply X1 and X2 's first column to the first column of U and X1 and X2 's second column on second column of U? I just could not write a code! it did not answer.

[Star Strider]

‘U’ is not a matrix. It is a row vector ‘ne’ elements long.

Answer 2

[dpb]

Sorry, I can't interpret what you're after...are the Xn intended to become the factors in U, respectively? If that's so, then simply

U=[X1 2*X2];