function - input and output matrix

I need to write a function that takes a matrix of any size, double all the elements that are positive and adds 10 to all the elements that are zero or negative. I can't use loops, only filters.

the input matrix is xin[n,m] sent by the script and the out variable is xout [n,m]

This is my code:

function xout = matrixfx(xin)
%matrixfx takes a matrix of any size, doubles all the elements that are positive and adds 10 to all
%the elements that are zero or negative.
[n,m] = size(xin);
xout = zeros(n,m);
mask = xin > 0;
xout(mask) = xin(mask) * 2;
xout(~mask) = xin(~mask) + 10;
end

[Steven Lord]

Okay, I can see one or two places where I might have suggestions on this code, but first what's your question about this code? What help are you looking for?

[Mina]

I need help to correct my mistakes.

I wrote a script to use the function and it is giving me this error "Operator '>' is not supported for operands of type 'struct'."

[Steven Lord]

Okay, can you show us that script? I have a suspicion about what's causing the error but I'd need to see that script to confirm or refute that suspicion.

[Mina]

In the script, the function is used to manipulate the test data and then the elements of the matrix are added up.

x = load ('matrixA.mat');

y = matrixfx(x);

[rows,cols] = size(y);

total = 0;

for i = 1:rows

for j = 1:cols

total = total + y(i,j);

end

end

Answer 1

[Steven Lord]

My suspicion was correct. When you call load with an output argument, that output argument is a struct array with each variable in the MAT-file you load stored as a field of that struct. You just need to pull the data out of the struct.

mydata = load('census.mat')

mydata = struct with fields:
    cdate: [21×1 double]
      pop: [21×1 double]

If I wanted to work with the date and population data from census.mat, I would need to use mydata.cdate and mydata.pop rather than mydata (the whole struct array), cdate (which doesn't exist; the data is in the field of mydata), or pop (which also doesn't exist.)

[p, s, mu] = polyfit(mydata.cdate, mydata.pop, 2); % Work with cdate and pop from census.mat

Answer 2

[Jan]

Your code is fine. The only problem is, that you call it with a struct. Unfortunately you show us the code, but not, how you cll it, but the error is there.

x = [-10, 0, 10;  -0.1, -1, 0];
matrixfx(x)  % Working!

ans = 2×3

0 10.0000 20.0000 9.9000 9.0000 10.0000

function xout = matrixfx(xin)
xout        = zeros(size(xin));
mask        = xin > 0;
xout(mask)  = xin(mask) * 2;
xout(~mask) = xin(~mask) + 10;
end