Why doesn't MATLAB support 'cpuArray' for some array creation functions?

For example, we can create a GPU array by code:

rand(3, 'single', 'gpuArray')

Unfortunately, this code will fail if it is run on a PC without a CUDA graphics card. If we can pass 'cpuArray' to rand, we can easily write a MATLAB program for both CPU and GPU computings. E.g.,

 useGpu = 0
 if(useGpu)
    arrayType = 'gpuArray';
 else
    arrayType = 'cpuArray';
 end

 % The program ...
 A = rand(3, 'single', arrayType);
 B = rand(3, 'single', arrayType);
 C = A*B;

(Unfortunately, this example doesn't work for current MATLAB...)

Otherwise, we have to write this code:

 useGpu = 0
 if(useGpu)
     A = rand(3, 'single', 'gpuArray');
     B = rand(3, 'single', 'gpuArray');
 else
     A = rand(3, 'single');
     B = rand(3, 'single');
 end
 C = A*B;

Could MathWorks add 'cpuArray' to most array creation functions in the future?

Answer 1

[Edric Ellis]

Another workaround is to use a cell array.

if useGpu
  arg = {'gpuArray'};
else
  arg = {};
end
A = rand(3, 'single', arg{:});

The {:} syntax converts arg into a comma-separated list.

[Meng-Yuan Huang]

Thanks. Your workaround is better, because we can specify data type for each array.

Answer 2

[Meng-Yuan Huang]

I find a workaround:

useGpu = 1;
if(useGpu)
    arg1 = 'single';
    arg2 = 'gpuArray';
else
    arg1 = 1;
    arg2 = 'single';
end

% The program ...
A = rand(3, 3, arg1, arg2);
B = rand(3, 3, arg1, arg2);
C = A*B