[RF] Test RooFit Hessians with Clad - #21622
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Test Results 23 files 23 suites 4d 15h 46m 8s ⏱️ For more details on these failures, see this check. Results for commit 5f67ec4. ♻️ This comment has been updated with latest results. |
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binNumber uses std::lower_bound, which clad can't differentiate. That was already handled for reverse mode by a dummy binNumber_pullback, but Hessians also run the forward pass over binNumber, and without a pushforward clad descends into std::lower_bound and warns about differentiating __builtin_constant_p and about unsupported typedef declarations, before failing outright. Declare the forward-mode counterpart, zero-valued for the same reason as the pullback: binNumber returns an integer, so it has no derivative. Since MathFuncs.h is compiled normally as well as parsed by cling, while clad::ValueAndPushforward only exists inside the interpreter, the type is forward-declared and the return type is kept dependent so that it is only completed when clad instantiates the template.
Clad generates a single std::pow pullback per session, so a function that
mixes an integral and a floating-point exponent makes clad::hessian() fail
with an int*/double* mismatch on the exponent adjoint:
error: cannot initialize a parameter of type 'double *' with an rvalue
of type 'int *'
note: passing argument to parameter '_d_exponent' here
That broke the Hessian of every likelihood containing a RooBernstein.
Casting the sign exponent to double is enough to keep both pow calls on
the same instantiation, and it does not change the result: the exponent
is integer-valued either way.
The code generated for a RooLognormal with useStandardParametrization() called
RooFit::Detail::MathFuncs::logNormalEvaluateStandard, which does not exist --
the function is called logNormalStandard. Any codegen or AD fit of such a pdf
failed to compile with "no member named 'logNormalEvaluateStandard'".
This went unnoticed because the LognormalStandard case in testRooFuncWrapper
builds its pdf with
Lognormal::model(x[...], mu[...], k[...], true)
and the factory quietly dropped that last argument, so the test was really a
duplicate of the Lognormal one. RooFactoryWSTool::asINT(), which is also the
conversion used for bool constructor arguments, is atoi(), and atoi("true") is
zero. Teach it about the spelled-out literals, which affects every factory
string that writes a bool that way, and makes the existing test exercise what
it says it does.
Verified that the generated code now agrees exactly with the reference backend,
for the nominal likelihood value and over a scan of the shape parameters.
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