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

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SUMMARY

The forum discussion addresses an "Undefined function or method 'qrfac' for input arguments of type 'double'" error encountered while implementing QR factorization in MATLAB 7.10.0 (R2010a). The issue arises from incorrect argument types being passed to the 'qrfac' function. Additionally, it highlights the importance of case sensitivity in MATLAB function names, recommending the use of 'qr(Q)' instead of 'QR(Q)' to avoid similar errors.

PREREQUISITES
  • Understanding of QR factorization algorithms
  • Familiarity with MATLAB programming, specifically version 7.10.0 (R2010a)
  • Knowledge of function argument types in MATLAB
  • Awareness of case sensitivity in MATLAB function calls
NEXT STEPS
  • Review MATLAB documentation for the 'qrfac' function
  • Learn about MATLAB's built-in functions for matrix operations
  • Explore error handling techniques in MATLAB
  • Study case sensitivity rules in MATLAB programming
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This discussion is beneficial for MATLAB developers, data scientists working with matrix computations, and anyone troubleshooting function errors in MATLAB programming.

andrea141
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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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