Updating a zeroized matrix with provided row vectors

Question

Damon Schmidt 2020-3-10

0
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https://ww2.mathworks.cn/matlabcentral/answers/510155-updating-a-zeroized-matrix-with-provided-row-vectors

评论： Damon Schmidt 2020-3-10

So I'm not sure if this can be done, but this is what I'm trying to do. I have a matrix (Force) that I've initialized to zero, it will always have three columns, but the rows will vary based on the nnd variable (determined by user input). Also based on user input is the Nodal Loads matrix, where Column 1 is the node number and column 2:4 are nodal loads. As you can see, there are nodes missing in the user input, meaning that if the user didn't input a value, then that nodal row remains zero. Is there a way to take the user input for Nodal_Loads and update the information into the Force matrix? My desired endstate is shown below. Thanks for the help.

Nodal_Loads = [2 0 -1000 0] %example 1

or

Nodal_Loads = [1 0 0 40; 3 -1000 0 40; 4 0 2000 40; 5 0 0 40; 8 1000 -2000 40; 9 0 0 40] %example 2

nnd = 9 %can be any number based on user input (I'll just say 9 for this example)

Force = zeros(nnd,3)

(Desired Endstate) %example 2

Force matrix now looks like:

Force = [0 0 40; 0 0 0; -1000 0 40; 0 2000 40; 0 0 40; 0 0 0; 0 0 0; 1000 -2000 40; 0 0 40]