MATLAB: Values from workspace change

MATLABmatrixvectorworkspace

I have a vector with values:

DH=[0 0 0 0 0 0 3.95 1009.15 0]

I insert the DH in a matrix

TimeofHomeArrival=[Home; DateVector(:,4).'; DateVector(:,5).'; DateVector(:,6).'; DH];

The values in the matrix are however now different than from the workspace

TimeofHomeArrival(5,:)=[ 0 0 0 0 0 0 4 127 0]

Best Answer

Home is an int8 array. When you combined the int8 data with the double data, the double data was converted to int8. See this documentation page and the "Largest and Smallest Values for Integer Classes" section on this documentation page for more information.

If you want to make TimeOfHomeArrival a double array you'll need to convert the int8 data into double by calling double on it.

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MATLAB: Sorting cell array ascending order and changing the values within the cell to positive

Try this:

>> A = {rand(2,3)-0.5,rand(1,3)-0.5,rand(3,3)-0.5};
>> [~,X] = sort(cellfun('size',A,1));
>> B = cellfun(@abs,A(X),'UniformOutput',false);

The cell array A represents your cell array, it contains three numeric arrays, with size Nx3 for N=[1,2,3]. The first cellfun measures the size of the first dimension of each numeric array, these sizes are then sorted into order, returning the sort index. Then the second cellfun sorts the cell array according to this index, and takes the absolute value of the numeric arrays.

MATLAB: It is necessary to declare the data type each time I change the value

MATLAB does not give you the ability to set a variable name as automatically a specific data type. (Unlike old Fortran, where I could tell it that all variables that begin with the letters i through n were of integer type automatically.)

So even though you initially assign

x = int8(9);

then when you do this:

x = 2;

MATLAB sees that 2 is a double precision value, and the assignment "x=" overrides the current datatype of x. So x is now a double.

You have two choices that I can think of.

x = int8(2);

must work of course, since that just overwrites x. But you can also use this form:

x(:) = 2;

x was initially a scalar, of class int8. But the assignment as x(:)= does not overwrite the variable type. It uses the current type of x. As a test try this:

x = int8(9);
whos x
Name      Size            Bytes  Class    Attributes
x         1x1                 1  int8               
x(:) = 2;
whos x
Name      Size            Bytes  Class    Attributes
x         1x1                 1  int8               
x
x =
  int8
   2

So x remains an int8, without needing to recast x as int8.

Best Answer

Related Solutions

MATLAB: Sorting cell array ascending order and changing the values within the cell to positive

MATLAB: It is necessary to declare the data type each time I change the value

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