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How to convert a matrix of double to int?

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I need to convert my matrix [648x2400 double] into integers value to use a mRMR function, but I do not know how to do that. I have tried to convert by uint8(matrix) or int8(matrix) but it does not give integers... And I always have this note: "Undefined function 'mrmr_mid_d' for input arguments of type 'int8' " (or double, or uint, and so on) can someone help me? thank you

Accepted Answer

Wayne King
Wayne King on 5 Dec 2013
Edited: Wayne King on 5 Dec 2013
I'm not sure what you are saying. Do you mean that:
X = 10+randn(16,16);
X = uint8(X);
Does not result in integers for the output in X?
The error message you report ("Undefined function 'mrmr_mid_d' for input arguments of type 'int8' ") just sounds like MATLAB cannot recognize the function, mrmr_mid_d.m.
You need to add the folder containing that function to the MATLAB path. You can launch
to add that folder.
  1 Comment
Emilie Mussard
Emilie Mussard on 5 Dec 2013
Thank you, I hadn't thought of the path problem and I focused on a wrong problem!

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More Answers (3)

Kelly Kearney
Kelly Kearney on 5 Dec 2013
It's possible that mrmr_mid_d.m isn't on your path; the other possibility is that it doesn't actually accept integer data types as input, but integer values stored as double arrays. In this case, you need to round your data in some manner (see round, ceil, floor, fix, etc)
x = rand(10)*10;
x = round(x);
mrmr_mid_d(x); % or whatever the syntax is...

MathWorks Support Team
MathWorks Support Team on 27 Nov 2018
To convert an array of type “double” to an integer type, you can use a function such as “int64”, which converts the input to a 64-bit integer. For example, consider the following:
x_double = [1 2 3];
x_int = int64(x)
For more information on integer types and functions, see
  1 Comment
Macro on 2 Jan 2024
Thank you for sharing. Great information! Converting a double array to an integer type is a common task in programming, and using the "int64" function for a 64-bit integer conversion is a smart approach. Your example is helpful for me.

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sixwwwwww on 5 Dec 2013
you can do it as follow:
a = randi(100, 4);
a = int64(a);
see following link for more information about integer data types:
Emilie Mussard
Emilie Mussard on 5 Dec 2013
Yes, it is what I have made. I thought that int64 (or int32, ...) was not the same type as int and so my function was not running on it, apparently I misunderstood and the problem is maybe in another place... Thank you for your prompt answer anyway!
Munawara Munia
Munawara Munia on 26 Apr 2016
Hi Emilie, I am facing the same problem. I ama also trying to use mRMR and getting the same errors. Could you kindly tell me what was the issues with your code and how you solved it..?? Badly need a solution about it. Thanks in advance. :)

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