How can I label a solution as NaN in a MEX code?

7 Ansichten (letzte 30 Tage)
AP
AP am 24 Jun. 2014
Bearbeitet: José-Luis am 24 Jun. 2014
I am using solvers of LAPACK libraries in a MATLAB MEX file for solving linear system of equations. For some of the cases, the system that I solve is singular. For example, the system is as follows for one of my cases:
A =
0.00000000 0.00000000 0.00000000
0.00000000 0.00000000 0.00000000
0.00000000 0.00000000 77.31867171
b:
-0.00000000 -0.00000000 -0.00000000
What would be the best approach to label this solution as NaN similar to MATLAB?

Akzeptierte Antwort

James Tursa
James Tursa am 24 Jun. 2014
Use the API function mxGetNaN:
E.g., to put a NaN value into a double for returning to the MATLAB workspace:
double d = mxGetNaN( );

Weitere Antworten (1)

José-Luis
José-Luis am 24 Jun. 2014
if (some_condition)
some_value = 0.0/0.0; %This will produce a NaN
end
  4 Kommentare
AP
AP am 24 Jun. 2014
Bearbeitet: AP am 24 Jun. 2014
Since I am writing a c++ code in MATLAB, I am trying to find a way to label the solution of a singular matrix to NaN in the c++ code. I am using LAPACK solvers to solve a linear system of equation. At some point the solution to this system fail and I want to be able to label this as NaN in my c++ code. Hope this clarifies my question.
José-Luis
José-Luis am 24 Jun. 2014
Bearbeitet: José-Luis am 24 Jun. 2014
double myNaN = 0.0/0.0;
will produce a NaN in C++. Alternatively, you could set it to some other value
double flag = numeric_limits<double>::max();
that you then change into NaN in Matlab.

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