Conditional expressions erroneously skip operations for AD<AD<double> > about cppad HOT 7 CLOSED

This bug has been verified; see
https://github.com/coin-or/CppAD/blob/master/bug/cond_exp.sh

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I have added a temporary (undocumented) feature
f.optimize("no_conditional_skip")
should work with the case above. This is a temporary fix that is necessary when the base type can correspond to variables. A better solution (which does automatic detection of this variability for each conditional expression) will be added to the wish list.

from cppad.

Thank you!
This fixes the issue as long as people remember to use this option.
Would it be possible to define default behavior for specific data types?
Some like this:

template<class Base>
struct CppADOptimizationOptions {
    static inline bool multiLevelADType() {
        return false;
    }
    // more option related methods here
};

template<>
template<class Base>
struct CppADOptimizationOptions<CppAD::AD<Base> > {
    static inline bool multiLevelADType() {
        return true;
    }
};

from cppad.

In the long term, I plan to add information to the tape that informs the
optimizer when a variables base type value is IdenticalPar
http://www.coin-or.org/CppAD/Doc/base_identical.xml#Identical.IdenticalPar
Even in the multilevel AD case, there can be conditional comparisons
that can be skipped (once this information is available on the tape). I
will not be able to work on this for a few months.

For this reason, I have not made
f.optimize("no_conditional_skip")
part of the CppAD API. If the plan above works, at this point I plan to
remove the option (with a message that explains it is no longer necessary).

Brad.

On 3/2/2015 3:13 AM, João Rui Leal wrote:

Thank you!
This fixes the issue as long as people remember to use this option.
Would it be possible to define default behavior for specific data types?
Some like this:

|template
struct CppADOptimizationOptions {
static inline bool multiLevelADType() {
return false;
}
// more option related methods here
};

template<>
template
struct CppADOptimizationOptionsCppAD::AD {
static inline bool multiLevelADType() {
return true;
}
};
|

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#7 (comment).

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I think that I have fixed this issue with the following commit
b564688
and it is not longer necessary to use the
f.optimize("no_conditional_skip")
option. The complication was the difference between parameters and variables at the AD and Base levels. The doxygen documentation for
https://github.com/coin-or/CppAD/blob/master/cppad/local/cskip_op.hpp
discusses this issue.

from cppad.

Thank you!
I tested with CppADCodegen and it works fine without the
"no_conditional_skip" argument.

2015-05-27 6:57 GMT+01:00 Brad Bell [email protected]:

Reopened #7 #7.

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#7 (comment).

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This issue has been fixed.

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