I’m getting the below error. Before A is assigned any values, it is an empty array, and the program is complaining that: number of columns of each array must match

size(A) = (0,)
size(b) = (26, 29)

Clearly, this is a bad habit I brought here from Matlab, so how do Julian folks get around this issue? Many thanks!

So I should do push!(A, b)? Unfortunately, it does not work either. How do I specify the fact that I want the item being pushed to be appended vertically?

The problem is that you can’t vcat a matrix and a vector. And even if your A were a matrix, you still can’t vcat a 26x29 matrix to a 0x0 matrix (for a vertical concatenation, the number of rows must match).

You could create a 0x29 matrix and then use vcat, but it should be easier to avoid this entirely using reduce:

reduce combines elements of a collection pairwise, and vcat does vertical concatenation, so reduce(vcat, ...) combines all the matrices in the collection by vertical concatenation. Julia actually has a special implementation (still in Julia, just written carefully) that makes that particular combination of operations more efficient than a naive approach. If you want to see how it works, you can do: @edit reduce(vcat, my_matrices)

using MAT
# Read the bathymetric values out of the mat file:
F1 = matopen("/test.mat");
A = read(F1, "A");
b = read(F1, "b");
close(F1);
A = reduce(vcat, [A, b])

Here is a link to download the “test.mat” file storing my data: