******** Bugs Problems and Features: MXYZPTLK ***************************
>>> 12/6/93 Two corrections were made to DA& DA::operator()( LieOperator& y ).
(a) The argument y is now checked explicitly to see if it is null. If
so, the value returned is the same as though y were zero. (Unless
*this is itsself null, in which case a null DA is returned. Perhaps
an error condition should be set for this instead???)
(b) The condition "if( p->weight != 0 )" and its consequent
are now correctly placed inside the scope of the
"for( i = 0; i < DA__1stEnv.DA__NumVar; i++ )" condition.
Also the line "u.reset();" was added near the top.
>>> 8/12/93 The LieOperator::expMap() and LieOperator::operator^
methods have now been implemented. The former integrates equations of
motion by developing exponential maps, and the latter simply evaluates
a Lie derivative. The one restriction at the moment is the assumption
made by .expMap() that the point of evaluation is a fixed point of the
vector field. There are ways of getting around this -- but, another
day. Demos are contained in files Lie_X_Test.cc, where X = A ... E.
__ This upgrade is significant enough to warrant a version change,
from 1.X to 2.0. Huzzah!
__ Addition has been modified so that small terms indistinguishable
from zero are not carried. Further, arithmetic on LieOperators has
been enabled.
>>> 7/20/93 Primitive garbage collection has been corrected within
MXYZPTLK v1.4. All DA type objects now have a disposable base class.
However, this is still not done correctly in the BEAMLINE class.
>>> 7/20/93 DA functions have been changed so that they return
DA& arguments. This should improve efficiency. New versions of
"new" and "delete" are under development. They are contained
between #ifdef POOLED and #endif POOLED statements and are NOT
activated by the Makefile.
>>> A ::norm() method should be written. This requires establishing
a scale for each coordinate via a DAScale function.