How can I write code to work with 1D matrices in Julia? -

consider following code

function test(m,b)     @show typeof(b)     all_u = rand(m,10)     one_u = all_u[:,1]     b*one_u end # works @show test(3, [1 1 1; 2 2 2]) # works @show test(2, [1 1; 2 2]) # fails @show test(1, [1; 2]) 

the last line fails with

`*` has no method matching *(::array{int64,1}, ::array{float64,1}) 

because b 1-d vector (which not ok), , one_u (which case, , doesn't cause issues).

how can write test(m,b) handle m==1 case doesn't require special casing m==1 (i.e. using if)? know m==1 case write method dispatch on fact b vector seems terribly wasteful.

quoting your follow-up comment:

b matrix, vector/1d matrix - that's problem.

you can convert vector 2d array "slicing" operation [:;:]. in other words, if b has type array{t,1}, b[:,:] has type array{t,2}:

julia> b = [1; 2] 2-element array{int64,1}:  1  2  julia> typeof(b[:, :]) array{int64,2} 

on other hand, if b has type array{t,2}, [:;:] no-op:

julia> b = [1 1; 2 2] 2x2 array{int64,2}:  1  1  2  2  julia> typeof(b[:, :]) array{int64,2}  julia> b[:, :] == b true 

therefore, in order accommodate function definition case m==1 (i.e. convert b 2d array when needed), can substitute b[:,:]*one_u b*one_u:

julia> function test(m, b)            @show typeof(b)            all_u = rand(m, 10)            one_u = all_u[:, 1]            b[:, :] * one_u        end test (generic function 1 method)  julia> @show test(3, [1 1 1; 2 2 2]) typeof(b) => array{int64,2} test(3,[1 1 1;2 2 2]) => [1.4490640717303116,2.898128143460623] 2-element array{float64,1}:  1.44906  2.89813  julia> @show test(2, [1 1; 2 2]) typeof(b) => array{int64,2} test(2,[1 1;2 2]) => [0.9245851832116978,1.8491703664233956] 2-element array{float64,1}:  0.924585  1.84917   julia> @show test(1, [1; 2]) typeof(b) => array{int64,1} test(1,[1,2]) => [0.04497125985152639,0.08994251970305278] 2-element array{float64,1}:  0.0449713  0.0899425