How to export to workspace a 4D array?

Basically the first function is generating values between a certain range. This values are indexes in order to have access to certain locations of the 4D array.

When writting mode is active, I save the value of 0.365 to the current location. At the end I would like to export the 4D array to workspace with all the stored values.

The 4D array has the following dimensions: [50 311 91 61] = 86318050 single values

However the array seems to be not able to be exported due to the size. I thought that changing it into single values will help but it seems to be too big.

Any ideas on how to fix this?

Answer 1

[Ameer Hamza]

Instead of using "To workspace" block, try using assignin(): https://www.mathworks.com/help/releases/R2020a/matlab/ref/assignin.html to directly save the values in the base workspace. For example, write the following line in your function

assignin('base', 'base_variable_name', array_filled)

[Mariana]

function [[out,array_filled] ]  = fcn(new, input, status, initial_array, export)
%Multidimensional array dimensions
xmin = 0; xmax = 200; xincr = 5;
ymin = -25; ymax = 25; yincr = 5;
zmin = 0; zmax = 180; zincr = 5;
hmin = -10; hmax = 10; hincr = 5;
xvec = xmin : xincr : xmax;
yvec = ymin : yincr : ymax;
zvec = zmin : zincr : zmax;
hvec = hmin : hincr : hmax;
x2xidx = @(xval) round((xval - xmin)/xincr) + 1;
y2yidx = @(yval) round((yval - ymin)/yincr) + 1;
z2zidx = @(zval) round((zval - zmin)/zincr) + 1;
h2hidx = @(hval) round((hval - hmin)/hincr) + 1;

persistent storage
persistent a_new

if isempty(storage)
    storage = initial_array;
    a_new = 0;
end

%(read only)
if status == 1
    a_new = storage(index1,index2,index3,index4);
end

%write only)
if status == 0
    storage(index1,index2,index3,index4);
    a_new = 50; 
end


if export == 1
    multi_array = storage;
else
    multi_array = single(zeros(nx,ny,nz,nh)); 
end


out = a_new;
array_filled = multi_array;

[Mariana]

I should change it like this?

function [[out,array_filled] ]  = fcn(new, input, status, initial_array, export)
assignin('base', 'multi_array', array_filled)

%Multidimensional array dimensions
xmin = 0; xmax = 200; xincr = 5;
ymin = -25; ymax = 25; yincr = 5;
zmin = 0; zmax = 180; zincr = 5;
hmin = -10; hmax = 10; hincr = 5;
xvec = xmin : xincr : xmax;
yvec = ymin : yincr : ymax;
zvec = zmin : zincr : zmax;
hvec = hmin : hincr : hmax;
x2xidx = @(xval) round((xval - xmin)/xincr) + 1;
y2yidx = @(yval) round((yval - ymin)/yincr) + 1;
z2zidx = @(zval) round((zval - zmin)/zincr) + 1;
h2hidx = @(hval) round((hval - hmin)/hincr) + 1;
persistent storage
persistent a_new
if isempty(storage)
    storage = initial_array;
    a_new = 0;
end
%(read only)
if status == 1
    a_new = storage(index1,index2,index3,index4);
end
%write only)
if status == 0
    storage(index1,index2,index3,index4);
    a_new = 50; 
end
if export == 1
    multi_array = storage;
else
    multi_array = single(zeros(nx,ny,nz,nh)); 
end
out = a_new;

[Ameer Hamza]

No, add this line at the end of your function definition like this

function [[out,array_filled] ]  = fcn(new, input, status, initial_array, export)
%Multidimensional array dimensions
xmin = 0; xmax = 200; xincr = 5;
ymin = -25; ymax = 25; yincr = 5;
zmin = 0; zmax = 180; zincr = 5;
hmin = -10; hmax = 10; hincr = 5;
xvec = xmin : xincr : xmax;
yvec = ymin : yincr : ymax;
zvec = zmin : zincr : zmax;
hvec = hmin : hincr : hmax;
x2xidx = @(xval) round((xval - xmin)/xincr) + 1;
y2yidx = @(yval) round((yval - ymin)/yincr) + 1;
z2zidx = @(zval) round((zval - zmin)/zincr) + 1;
h2hidx = @(hval) round((hval - hmin)/hincr) + 1;
persistent storage
persistent a_new
if isempty(storage)
    storage = initial_array;
    a_new = 0;
end
%(read only)
if status == 1
    a_new = storage(index1,index2,index3,index4);
end
%write only)
if status == 0
    storage(index1,index2,index3,index4);
    a_new = 50; 
end
if export == 1
    multi_array = storage;
else
    multi_array = single(zeros(nx,ny,nz,nh)); 
end
out = a_new;
assignin('base', 'multi_array', array_filled)

[Mariana]

But I need to remove the "to workspace" block?

[Ameer Hamza]

Yes, you should remove it. assignin will already save values in the base workspace.

[Mariana]

Function 'assignin' not supported for code generation.

Function 'MATLAB Function' (#132.4706.4751), line 154, column 1:
"assignin('base', 'array_filled', multi_array)"
Launch diagnostic report.

[Ameer Hamza]

Oh! I forgot it does not support code generation. Change the function definition to this

function [[out,array_filled] ]  = fcn(new, input, status, initial_array, export)
coder.extrinsic('assignin') % <===== added this line
%Multidimensional array dimensions
xmin = 0; xmax = 200; xincr = 5;
ymin = -25; ymax = 25; yincr = 5;
zmin = 0; zmax = 180; zincr = 5;
hmin = -10; hmax = 10; hincr = 5;
xvec = xmin : xincr : xmax;
yvec = ymin : yincr : ymax;
zvec = zmin : zincr : zmax;
hvec = hmin : hincr : hmax;
x2xidx = @(xval) round((xval - xmin)/xincr) + 1;
y2yidx = @(yval) round((yval - ymin)/yincr) + 1;
z2zidx = @(zval) round((zval - zmin)/zincr) + 1;
h2hidx = @(hval) round((hval - hmin)/hincr) + 1;
persistent storage
persistent a_new
if isempty(storage)
    storage = initial_array;
    a_new = 0;
end
%(read only)
if status == 1
    a_new = storage(index1,index2,index3,index4);
end
%write only)
if status == 0
    storage(index1,index2,index3,index4);
    a_new = 50; 
end
if export == 1
    multi_array = storage;
else
    multi_array = single(zeros(nx,ny,nz,nh)); 
end
out = a_new;
assignin('base', 'multi_array', array_filled)

[Mariana]

You were right. It works now.

Thanks a lot!

[Mariana]

Is it possible to load a variable in simulink workspace of 400MB?

[Ameer Hamza]

I am not sure. Maybe you can try the constant block to load the value in Simulink workspace. Otherwise, you can again use evalin(), opposite of assignin, to directly read the value from the base workspace. Another approach (preferable) is mentioned in Rubem's answer here: https://www.mathworks.com/matlabcentral/answers/110060-simulink-matlab-function-block#answer_385817

[Mariana]

I have added the variable of 400MB into the simulink workspace, but I am not able to compile the model. I have an error message that there is no heap space, any suugestion on how to solve this issue?

[Ameer Hamza]

I haven't worked with Simulink compiler, so I don't know about this issue. Maybe the following will be helpful

https://www.mathworks.com/matlabcentral/answers/262442-java-heap-space-out-of-memory-problem

https://www.mathworks.com/matlabcentral/answers/101761-how-can-i-handle-a-tlc-compiler-out-of-memory-error-upon-generating-code-for-a-simulink-model-on-a-n