Fix memory leak in umfpack_numeric!

[cfauchereau]

Fix #37118
If umfpack_numeric! is called on a UmfpackLU struct that has already been factorized, its pointer "numeric" is overwritten without freeing the pointed Numeric object.

This simple fix does:

• Check for an existing Numeric object before writing to UmfpackLU.numeric.
• If it exists, free the object.

[dkarrasch]

Just a quick style comment: indention is slightly off (by two characters?). These one-line branches are often written as

U.numeric != C_NULL && umfpack_free_numeric(U)

[cfauchereau]

Just a quick style comment: indention is slightly off (by two characters?). These one-line branches are often written as

U.numeric != C_NULL && umfpack_free_numeric(U)

I made the change. It was a tab, my mistake.

[dkarrasch]

Just to make sure: did you check that the performance benefits (of lu! over lu) are still preserved?

[cfauchereau]

Just to make sure: did you check that the performance benefits (of lu! over lu) are still preserved?

lu! is still faster than lu. The benefit comes from the reuse of the Symbolic object, the Numeric object is recreated each time. reuse_numeric is a misleading variable name.

EDIT: reuse_numeric is fine, it is another optimization.

[andreasnoack]

Thanks. I wonder if we ever manage to wrap these functions correctly.

[andreasnoack]

Do we just ignore FreeBSD failures for the time being?