Finding the differential of an expression with multiple variables

1 reply · 2K views · last reply
ssafdarpk
Messages
1
Reaction score
0
Can someone help me understand the answer to this differential?

I have the following expression
Product of three matrices: a 4x2 matrix with entries 1 - x/L, 0, x/L, 0 and 0, 1 - x/L, 0, x/L; a 2x4 matrix with entries +L d/dH0(dH0/dx), +L d/dH1(dH1/dx) and -L d/dH0(dH0/dx), +L d/dH1(dH1/dx); and a 4x2 matrix with entries 1 - x/L, 0, x/L, 0 and 0, 1 - x/L, 0, x/L.
where
Equation H_i = [1 - x/L, x/L] times the column vector (H_i^1, H_i^2), where H_i is written as a row vector of shape functions multiplying nodal values.

Now what I can understand the differential of
Equation: partial of H_i with respect to x equals a row vector [-1/L, 1/L] multiplied by the column vector [H_i^1, H_i^2].

what will be the following?
Handwritten expression: partial derivative with respect to H_i of the partial derivative of H_i with respect to x, followed by =??
 
ssafdarpk said:
where
Equation H_i = [1 - x/L x/L] times column vector (H_i^1, H_i^2), a 1 by 2 row of shape functions multiplied by a 2 by 1 column of nodal values.

Now what I can understand the differential of
Handwritten equation: partial H_i over partial x equals a row vector [-1/L, 1/L] times a column vector of H_i^1 and H_i^2.
From these equations it seems [tex]\frac{\partial H_i^j}{\partial x}=0[/tex] holds. Could you tell me physical meaning or background of the first 4x4 quantity for further investigation ?
 
Last edited: