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HELP FOR: gralter, grcalcalter
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CALLING SEQUENCE: gralter ( objectSeq )
gralter ( objectSeq, simp )
gralter ( objectSeq, simp1, simp2, ... )
grcalcalter ( objectSeq, simp1, simp2, ... )
PARAMETERS: objectSeq - object name or sequence of object names
simp - (optional) simplification code(s) instructing
which simplification routine to apply to the
named objects
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SYNOPSIS:
- gralter() and grcalcalter() allow modification of GRTensorII objects through
the use of the standard MapleV simplification/expansion routines.
- Both routines require a GRTensorII object name as the first argument.
Further GRTensorII objects may be listed separated by commas.
- If no simp argument is specified, a menu is displayed giving a list
of standard choices for simplification routines. The list is as
follows:
0) none
1) simplify() try all simplification techniques
2) simplify[trig] apply trig simplification
3) simplify[power] simplify powers, exp and ln
4) simplify[hypergeom] simplify hypergeometric functions
5) simplify[radical] convert radicals,log,exp to canonical form
6) expand()
7) factor()
8) normal()
9) sort()
10) simplify[sqrt,symbolic] allows sqrt(r^2) = r
11) simplify[trigsin] trig simp biased to sin
12) Apply constraint equations
13) Apply constraints repeatedly
14) other user-specified routine
The user is prompted to enter a digit corresponding to the desired
simplification to be applied to each component of each object specified
in the objectSeq argument.
1 ... 11 apply the named MapleV simplification routine. See the
corresponding MapleV help pages for more details on
the functioning of these routines.
12 applies any constraint equations that were specified with the
metric or using the grconstraint function [see the help
page for grconstraint].
13 applies the constraint equations repeatedly until the given
expression no longer changes.
14 the user is prompted to provide the name of a routine which will
be applied to each component of the named GRTensorII objects.
- The simp parameters can be used to avoid the menu and apply the named
simplifications directly. These parameters can take one of three forms:
i) A digit 1 ... 13 corresponding to the menu options listed above;
ii) A name corresponding to the options listed above. Recognized names are
simplify, trig, power, hypergeom, radical, expand, factor,
normal, sort, sqrt, trigsin, cons, consr
iii) If a desired routine does not exist in the above list, its name can
be supplied directly (eg. radsimp). [Note that the routine must
function with only one argument. To apply a function of more than
one argument, see grmap().]
- gralter() is used on an object that has already been calculated.
- grcalcalter() allows simplification to take place during the calculation.
Note that this means all precursor objects whose calculation is required
will be altered in the same fashion.
- In the case of some of the scalar invariants the use of grcalcalter()
avoids a MapleV `Object Too Large' error. For example, the Kerr-Newmann
metric will generate this error when trigonometric simplification is
applied after using normal as the default simplification, but grcalcalter()
with trigonometric simplification is successful.
- If the global variable grOptionAlterSize is set to true the size of
each altered component will be displayed. This allows the user to
determine if an object has been reduced to a "displayable" size.
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EXAMPLES:
> gralter ( R(dn,dn,dn,dn), 2 ):
Component Alteration of a grtensor object:
Applying routine simplify[trig] to object R(dn,dn,dn,dn)
> gralter ( R(dn,dn,dn,dn), trig ):
Component Alteration of a grtensor object:
Applying routine simplify[trig] to object R(dn,dn,dn,dn)
> gralter ( R(dn,dn), radsimp ):
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SEE ALSO: grmap, grdisplay, grt_objects, groptions.
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