This is effectively a revert of commits 1b4f68f934,
32fb90d5f3 and f6f4ea70fb.
This transformation had been introduced in order to fix the computation of the
Ramsey steady state in the case where Lagrange multipliers appeared with a lead
or lag ⩾ 2 (and where thus part of the definition of an auxiliary variable).
But this transformation had introduced bugs in the handling of external
functions which were difficult to tackle.
Moreover, it seems preferable to keep the strict correspondence between the
dynamic and static model, in order to make reasoning about the preprocessor
internals easier (in particular, for this reason this transformation was not
implemented in ModFile::transformPass() but in ModFile::computingPass(), which
was a bit confusing).
A better solution for the Ramsey steady state issue will is implemented in the
descendent of the present commit.
Ref. dynare#633, dynare#1119, dynare#1133
– a generic one: CommonEnums.hh
– and a bytecode-specific one: Bytecode.hh
By the way, rename global constant “near_zero” into “power_deriv_near_zero”,
for clarity.
When an endogenous is declared with “var(log)”, say “y”:
– creates an auxiliary named “LOG_y”
– replaces “y(±l)” everywhere by “exp(LOG_y(±l))”
– adds a new auxiliary equation “y=exp(LOG_y)”
– adds a new definition “LOG_y=log(y)” in set_auxiliary_variables.m and
dynamic_set_auxiliary_series.m files
This option also works in conjunction with “deflator=…”, such as “var(log,
deflator=…)” (the “log” must appear befor “deflator”). There are no provisions
for combining “log” with “log_deflator”, because that would not make much sense
from an economic point of view (amounts to taking the log two times).
Ref. dynare#349
This is a more natural semantics.
Incidentally, this fixes a bug in the variable mapping (M_.mapping) where some
endogenous, appearing in a log() in a VAR or TCM, would not be mentioned (e.g.
in the var-expectations/7/example1.mod test, and many others).
By the way:
– Fix and improve the explanation of the purpose of the orig_symb_id and
orig_lead_lag fields for auxvars
– Factorize the code that prints those fields in MATLAB and JSON output
The logic was flawed in several ways. In particular, the test files
pac/trend-component-{3,10,11}/example1.mod would return A0 and A0star matrices
where the (2,2) element was incorrectly zero.
The case of a diff aux var corresponding to a complex expression was not
correctly handled, and could lead to a value -1 being returned by these
methods.
Also be more strict on the form of the target (must now be X(-1) or log(X(-1))
where X is *not* an auxiliary variable).
By the way, improve some comments in SymbolTable.
We can therefore manipulate objects by value rather than by pointers, which
saves a lot of memory manipulations (and avoid potential segfaults and memory
leaks).
Note that there is no default action ("$$ = $1") when using the variant type,
so we add them explicitly.
In the absence of this option, if a var_model statement(s) is present, then aux vars/eqs are created for the same types of unary operators but only for equations specified in the var_model statement
In the absence of both this option and var_model statements, no unary op auxiliary variables are created
diffs continue to be substituted everywhere; for the moment auxiliary variables are created for diffs of expressions. A forthcoming change will allow auxiliary variables created for diffs of expressions to be linked with their lagged expressions as is currently the case for diffs of variables
Sébastien Villemot
Houtan Bastani