Why Am I Getting an Undefined Function Error for 'double' in QR Factorization?

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The discussion revolves around an error encountered when attempting to compute the QR factorization of a matrix using a function called 'qrfac'. The error message indicates that the function is undefined for input arguments of type 'double', suggesting a mismatch in expected argument types. Participants recommend checking the documentation for 'qrfac' to ensure the correct argument types are being used. Additionally, a user mentions a similar issue in MATLAB, where they mistakenly used 'QR' instead of the correct 'qr' function, highlighting that MATLAB function names are case sensitive. The key takeaway is to verify function names and argument types to resolve the errors.
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Error message using 'double' ??

I'm writing a function with the algorithm to compute the QR factorization of the matrix A, when I go to use my function and input a matrix A I get the error message

Undefined function or method 'qrfac' for input arguments of type 'double'

and I have no clue what I'm doing wrong. Help please!

Andrea
 
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andrea141 said:
I'm writing a function with the algorithm to compute the QR factorization of the matrix A, when I go to use my function and input a matrix A I get the error message

Undefined function or method 'qrfac' for input arguments of type 'double'

and I have no clue what I'm doing wrong. Help please!

Andrea

You haven't provided much information, but from the error message, you are probably not providing the right types of arguments to qrfac. Look at the documentation for qrfac, and make sure that the arguments in your call to qrfac are the same types as it expects.

Is this fortran code you're writing?
 


I have identical problem on MATLAB 7.10.0 (R2010a):

Q =

0.4472 0 0 0 0
0.4472 1.0000 0 0 0
0.4472 0 1.0000 0 0
0.4472 0 0 1.0000 0
0.4472 0 0 0 1.0000

[QQ,RR,EE]=QR(Q)
? Undefined function or method 'QR' for input arguments of type 'double'.

any clue?
 


patiobarbecue said:
any clue?
Use qr(Q) rather than QR(Q). Matlab's built-in function names are case sensitive.
 
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