 Parameters - Maple Help

Modifiable Options within the gfun Package Calling Sequence Parameters(arg1, arg2, ... ) Parameters

 arg1, arg2, ... - argument(s) of the form name=val or name Description

 • The Parameters command is used to set and query variables that affect the computation inside gfun. The variables that can be set and queried are as follows.

 maxdegcoeff maxordereqn maxdegeqn mindegcoeff mindegeqn minordereqn optionsgf

 • If an argument is of the form name=val then this specifies the setting for the named variable.
 For each argument of this type, Parameters returns the old value of the argument.  This is convenient when you want to change and later restore a value, for example,

 oldorder := Parameters(maxordereqn=7);    # set new value and save old ... Parameters(maxordereqn=oldorder);         # restore previous value

 • If an argument is a name then the current value of the named variable is retrieved and returned as the function value.
 • When Parameters is called with many arguments, it returns an expression sequence containing the values.
 • The standard set of Parameters variables is:

 NAME VALUES EXPLANATION maxdegcoeff nonnegint the maximal degree of the coefficients of equations returned by listtodiffeq, listtoalgeq, seriestodiffeq, and seriestoalgeq.  The default value is $4$. maxdegeqn nonnegint the maximal degree for polynomial equations returned by listtoalgeq and seriestoalgeq.  The default value is $3$. maxordereqn nonnegint the maximal order for differential equations returned by listtodiffeq and seriestodiffeq.  The default value is $3$. mindegcoeff nonnegint the minimal degree of the coefficients of equations returned by listtodiffeq, listtoalgeq, seriestodiffeq, and seriestoalgeq.  The default value is $0$. mindegeqn nonnegint the minimal degree for polynomial equations returned by listtoalgeq and seriestoalgeq.  The default value is $2$. minordereqn nonnegint the minimal order for differential equations returned by listtodiffeq and seriestodiffeq.  The default value is $1$. optionsgf list specifies the list of types of generating functions considered by listtoalgeq, listtodiffeq, listtohypergeom, listtolist, listtoratpoly, listtorec, listtoseries, seriestoalgeq, seriestodiffeq, seriestohypergeom, seriestolist, seriestoratpoly, seriestorec, and seriestoseries. The default is ['ogf', 'egf'] (ordinary and exponential generating functions).

 For more information on the generating function types, see gfun/gftypes.
 For example, if the listtodiffeq function is used, only those linear differential equations whose order is between minordereqn and maxordereqn and whose coefficients have a degree between mindegcoeff and maxdegcoeff are considered.
 • Similarly, maxdegeqn and mindegeqn are used to bound the degree of algebraic equations.
 • Note, the old way of changing parameters by assigning the values to gfun:- Examples

 > $\mathrm{gfun}:-\mathrm{Parameters}\left('\mathrm{maxordereqn}'=5,\mathrm{mindegcoeff}\right)$
 ${3}{,}{0}$ (1)