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## 7 Flags

Flag: prompt string

If one changes the prompt, string is a string of alphanumeric characters without quotes. After this command is executed, subsequent commands will cause new prompts to be obtained from string by incrementing it. If the prompt ends in a letter, it will be treated as a digit in base 26 and incremented. If it ends in a string of digits, that string will be treated as a number in base 10 and incremented. The remaining characters in the string will play no role in this incrementation.

e1 : set prompt az9Z;
e1 : a+b;

az9Z: a + b

az9AA : a+b;

az9AA: a + b

az9AB : set prompt ok99;
az9AB : a+b;

ok99: a + b

ok100 : a+b;

ok100: a + b

ok101 :

Flag: ingrammar grammar
Flag: outgrammar grammar

The following examples show how one changes the input grammar or the output grammar.

e1 : a:[[[1,2,3]]];

e1: [[1, 2, 3]]

e2 : set outgrammar standard;
e2 : a;

e2: [[[1, 2, 3]]]

e3 : set outgrammar scheme;
e3 : a;

(define e3 #(#(#(1 2 3))))
e4 : (1+x)^5;



(define e4 (+ 1 (* 5 x) (* 10 (^ x 2)) (* 10 (^ x 3)) (* 5 (^ x 4)) (^ x 5)))
e6 : set ingrammar scheme;
e6 : (+ e4 1);

(define e6 (+ 2 (* 5 x) (* 10 (^ x 2)) (* 10 (^ x 3)) (* 5 (^ x 4)) (^ x 5)))
e7 : (set ingrammar disp2d)
e7 : diagmatrix(3,6);

(define e7 #(#(3 0) #(0 6)))
e8 : set outgrammar disp2d;
e8 : e7;

[3  0]
e8: [    ]
[0  6]

e9 : set outgrammar standard;
e9 : e7;

e9: [[3, 0], [0, 6]]


Note that in the above examples, it is possible to input and output expressions in scheme by setting the ingrammar and/or outgrammar to scheme. Doing so result in linear output (as with standard grammar) as opposed to a two dimensional display (as with disp2d). The analogue of disp2d for scheme output is scheme pretty-printing. To have such output, set the output grammar to schemepretty.


e4 : set outgrammar schemepretty;
e4 : (1+x)^5;

(define e4
(+ 1
(* 5 x)
(* 10 (^ x 2))
(* 10 (^ x 3))
(* 5 (^ x 4))
(^ x 5)))


Jacal also allows for output to be automatically typeset in TeX. This can be quite useful if one wants to use the results of one’s computations in published articles. Continuing with the example of (1+x)^5 above, we have:

e5 : set outgrammar tex;
e5 : e4;

e5: 1 + 5 x + 10 x^{2} + 10 x^{3} + 5 x^{4} + x^{5}

e6 : (1+1/x)^3/(1-1/y)^4;

e6: {\left(1 + 3 x + 3 x^{2} + x^{3}\right) y^{4}}\over{x^{3} - 4 x^{3} y +

6 x^{3} y^{2} - 4 x^{3} y^{3} + x^{3} y^{4}}

Flag: priority int

The following examples show how to set the priority of printing terms.

e10 : a;

e10: [[[1, 2, 3]]]

e11 : show priority a;

;;; not a simple variable:  (((1 2 3) . ()) . ())

e12 : show priority b;

e12: 128

e13 : show priority c;

e13: 128

e14 : b+c;

e14: b + c

e15 : c+b;

e15: b + c

e16 : set priority b 200;
e16 : b+c;


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