Using min() on vectors with double

I have several variables of the double type, each around 450x1 in size. I would like to find the minimum value of each of them, but when I use min(vector), MATLAB returns "Subscript indices must either be real positive integers or logicals." Does this mean that min() cannot work with decimals? If so, is there another function I can use that will? An example of my code is below. As you can see, I have set up a matrix that has two columns, one with a single integer and another with the minimum value of the vector.

min_set = [974,min(blg0974);975,min(blg0975);976,min(blg0976)];

Update: All my vectors have positive values with decimal places up to the ten thousandth's place.

[Stephen]

min should work with double type. The error message you reported and the line supplied leads me to believe there is a variable in your workspace named "min". Is that the case?

Answer 1

[Geoff Hayes]

Kylie - try typing

 which min

to see if min refers to the function to find the minimum value of an array or if min refers to a local variable. If you are seeing the above error message when you call min(vector), then this suggests that you are trying to access elements in an array named min with non-integer indices (which would be the floats or doubles in your vectors/arrays). If this is the case, then you can easily fix this problem by renaming your local variable to something else which will not correspond to a built-in MATLAB function.

[Kylie Hansen]

I wasn't familiar with the which command. I've learned something new today! Thank you so much. The issue is solved, and I can go back to work headache-free.

Answer 2

[dpb]

"when I use min(vector), MATLAB returns "Subscript indices must either be real positive integers or logicals."

This means you've inadvertently aliased the MIN() function and Matlab now sees min(blg0974) as an array reference.

To confirm this diagnosis, execute

which min

and it will return "min is a variable". To fix this problem, execute

clear min

and remember to not do that again! :)

Illustration of the above to reproduce your symptom:

>> min=min(rand(3))  % call MIN(), forget and name output as min, too...
min =
  0.5936    0.2439    0.3485
>> min(min)          % try to get overall minimum of the column minima above
Subscript indices must either be real positive integers or logicals. 
>>

Oops! Look familiar? :)

>> which min           % Whassup???
min is a variable.       % Aha!  Of course and arrays can't have fractional subscripts
>> clear min             % fix the mistake...
>> which min             % and back to normal...
built-in (C:\ML_R2014b\toolbox\matlab\datafun\@logical\min)  % logical method
>>

[Kylie Hansen]

Thank you for such a detailed response. I am familiar with the mistake of naming variables after functions, but I had too many variables in my workspace that I hadn't noticed that I had set it as such. I will definitely keep your advice in mind! Thanks again.

Answer 3

[Giovanni D'Avanzo]

what'is blg0974 ?

Answer 4

[PARAS PATIL]

nothing