Hi,
I am trying to use DGEQR2 to calculate QR factorization of a rectangular
matrix. I was able to compile the library and run it with a simple 4x3 case. I
also could see R (which is the upper triangular portion of A on exit).
However, I am having some issue on extracting Q from the matrix.
In the documentation it is written that Q is the product of elementary
reflectors (H(1)H(2)...H(k)), where H(i) = I  tau*v*v_transpose and v is
stored in the lower triangular portion of A on exit. This involves a lot of
calculations outside the library. Is there any easier way to calculate Q? I am
not sure about what are the properties of elementary reflectors and properties
of v, we can use to simplify the calculations.
Any help in this matter will be greatly appreciated.
Thanks,
Roy
===============================================================
Associate Professor
Mailing Address:
Mechanical Engineering/UAB
BEC 257
Phone: (205)9340832 /Fax:(205)9757244 1720
Second Ave South
http://www.eng.uab.edu/me/faculty/rkoomul
Birmingham, AL 35294
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