Magma provides a history system which allows the recall and editing of previous lines. The history system is invoked by typing commands which begin with the history character `%'. Currently, the following commands are available.

%p

List the contents of the history buffer. Each line is preceded by its history line number.

%pn

%pn_1 n_2

%P

List the contents of the history buffer. The initial numbers are not printed.

%Pn_1 n_2

%s

List the contents of the history buffer with an initial statement for each line to reset the random number seed to the value it was just before the line was executed. This is useful when one wishes to redo a computation using exactly the same seed as before but does not know what the seed was at the time.

%sn_1 n_2

%S

As for the seed has changed since the previous time it was printed. Also, it is not printed if it would appear in the middle of a statement (i.e., the last line did not end in a semicolon).

%Sn_1 n_2

%

Reenter the last line into the input stream.

Reenter the line specified by line number n into the input stream.

%n_1 n_2

Reenter the history lines in the range n_1 to n_2 into the input stream.

Edit the last line. The editor is taken to be the value of the EDITOR environment variable if is set, otherwise "/bin/ed" is used. If after the editor has exited the file has not been changed then nothing is done. Otherwise the contents of the new file are reentered into the input stream.

%en

Edit the line specified by line number n.

%en_1 n_2

Edit the history lines in the range n_1 to n_2.

Execute the given command in the Unix shell then return to Magma.