[petsc-dev] Fwd: Changes in PETSc

Matthew Knepley knepley at ci.uchicago.edu
Tue Aug 21 10:39:08 CDT 2012

Wolfgang is not wrong here. I was against the name change :)


---------- Forwarded message ----------
From: Wolfgang Bangerth <bangerth at math.tamu.edu>
Date: Mon, Aug 20, 2012 at 10:30 PM
Subject: Changes in PETSc
To: Matthew Knepley <knepley at ci.uchicago.edu>, "Toby D. Young" <
tyoung at ippt.gov.pl>

Hi Matt,
I ran across something today that I believe perfectly illustrates the kind
of thing that drives everyone completely mad about PETSc's habit of
changing everything in every release. I was staring for a long time at a
patch by one of our contributors labeled "fix catastrophic typo" that reads
like this:
-    int ierr = KSPSetType (ksp, const_cast<char *>(KSPCHEBYSHEV));
+                                     // set the type of solver.
+    int ierr;
+#ifdef DEAL_II_PETSC_VERSION_LT(3,3,**0)
+    ierr = KSPSetType (ksp, const_cast<char *>(KSPCHEBYCHEV));
+    ierr = KSPSetType (ksp, const_cast<char *>(KSPCHEBYSHEV));
It took me minutes to find the difference: before 3.3, the name was spelled
chebyChev, after that chebyShev. That's really a completely unnecessary
change -- but hugely disruptive because not compatible, incredible
difficult to see, and it also has no real value at all: whether you want to
spell the name the French or the American way really makes no difference at
all. Worst of all, it would have been absolutely trivial to make the change
backward compatible by simply doing
but that didn't happen.

So why do it? Sorry for venting, but it just doesn't make sense to me...

Wolfgang Bangerth               email:            bangerth at math.tamu.edu

What most experimenters take for granted before they begin their
experiments is infinitely more interesting than any results to which their
experiments lead.
-- Norbert Wiener
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