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dgels (or dgels_): reuse already allocated memory / meaning of parameter trans_len

Question asked by robertolemoine on Sep 6, 2013
Latest reply on Sep 6, 2013 by chipf

Dear all,

 

I would like to solve a linear least squares problem with dgels (or dgels_). It is crucial for me to avoid any memory allocation besides the one made at compile time. To avoid this, I intend to recycle a large chunk of memory which I have already available in my program.

 

As far as I understand, using dgesl_ gives the possibility to provide a pointer to external memory in its argument "double *work" (as declared in acml.h, v. 5.3.0). Here is where I would like to use my available memory chunk. However, I find nowhere in internet what the last argument of dgesl_ ("int trans_len") is supposed to mean.

 

So, my two questions are:

a) Is it true that my only option to recycle memory for the workspace is to use dgesl_ instead of dgesl? (I don't see how calling degsl alone can manage to recycle memory, as it does not have an argument for it).

 

b) What does the argument trans_len in dgesl_ mean?

 

Thanks a lot in advance.

 

Kind regards,

 

Roberto Lemoine

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