Macaulay parameters

 

Macaulay has a set of parameters which are used to control display or computing. The values of these parameters can be viewed or set using the set and incr-set commands.

auto

This integer flag, if greater than zero, instructs the system to not perform auto-reduction on the elements of a standard basis. If this variable is set to a positive number, the calculations will slow down very dramatically. Thus, it is perhaps crazy to even think about changing the value of this variable. The default is 0.

autocalc

This integer flag, if not equal to zero, instructs the computation commands (std, lift-std, res, nres, syz, intersect, modulo, and quotient) to automatically start their computations. If the value of this flag is negative, the above computations are performed to completion. If the value is positive, the commands compute their results through degree d, where d is the value of the ``autodegree'' set variable below. The default value is -1.

autodegree

This integer value describes the highest degree to which to compute during computations. This flag is only active if the ``autocalc'' flag is set to a positive value. The default value is 0.

char0

This integer flag, if zero, instructs Macaulay to attempt to lift all numbers mod p to rational numbers. This lifting is done for display only: no change in the internal representation of numbers ever occurs. If this flag is positive, then each coefficient of each polynomial is displayed without lifting. The default value is 0.

echo

This integer flag, if greater than zero, instructs Macaulay to echo onto the screen everything which the user types. This is useful when the input is coming from somewhere other than the users keyboard. For example, when using MPW and command files on a Macintosh, or when using emacs on Unix systems. The default value is 0.

linesize

The maximum width (in number of characters) of a displayed matrix. This should be set to the width of the screen. The default value is 79.

maxdegree

This integer value describes the maximum degree of a monomial in a ring. In the ring command, this maximum degree is used to determine internal monomial tables. Depending on the monomial order chosen, the actual maximum degree may be much smaller than this value. For example, if a ring has one block of 100 variables, then the maximum degree is 6. However, if a block of variables has only several variables, then ``maxdegree'' is used. For example, if a ring has a block with one variable, and ``maxdegree'' is set to 1000, then the maximum degree of this variable in any monomial is 1000. Currently, the limit on ``maxdegree'' is about 12000. The default value is 512.

nlines

The number of blank lines which Macaulay displays between commands. The default value is 1.

prcomment

This integer flag, if positive, instructs Macaulay to display a leading semicolon in front of any displayed values. This is useful in conjunction with monitoring a Macaulay\ session: the resulting log file can then be used as input to Macaulay. The default value is 1.

prlevel

This integer flag, if larger than zero, instructs the system to suppress all output to the user's screen. This is very useful for having certain commands work quietly. Beware though, that all output is silenced: this includes the Macaulay\ prompt, making it hard to tell what is going on. For this reason, this is used mainly in command files: the first line of the command file increments prlevel and the last line decrements it, using the incr-set command.

Note that in a command file, Macaulay usually echos to the screen the commands in the file. However, Macaulay does a special check to see if the command is ``set prlevel 1'', or ``incr-set prlevel 1''. If so, this line is not echoed. Thus, in a command file, these lines are never displayed, allowing the file to act silently.

showmem

This integer flag, if positive, instructs Macaulay to display memory usage at every increase (currently about every 64 Kbytes). Default value is 1.

timer

This integer flag, if larger than zero, tells Macaulay to display the amount of time used for each command. If the amount of time is less than one second, nothing is displayed. On multi-user systems, this time records the amount of time the system used for Macaulay, not the time it used to process everyone. The default value is 0.

verbose

This integer flag, if larger than zero, displays extra feedback information during certain computations. The commands which display extra information are the computation commands (see Chapter 7), reduce, lift, hilb, codim, degree, wedge, hulb and hull. The exact information displayed is described with the particular command. The default value is 0.

The commands for manipulating these parameters are the following.