Display a linear combination: Difference between revisions

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=={{header|RPL}}==

RPL can handle both stack-based program flows and algebraic expressions, which is quite useful for tasks such as this one.

{{works with|Halcyon Calc|4.2.7}}

===Straightforward approach===

This version has the disadvantage of sometimes interchanging some terms when simplifying the expression by the COLCT function.

≪ → scalars

≪ '0' 1 scalars SIZE FOR j

scalars j GET

"e" j →STR + STR→ * +

NEXT

COLCT COLCT

≫ ≫

'COMB→' STO

===Full-compliant version===

The constant π is here simply used to facilitate the construction of the algebraic expression; it is then eliminated during the conversion into a string.

≪ → scalars

≪ "" 1 scalars SIZE FOR j

'π' scalars j GET "e" j →STR + STR→ * + →STR

OVER SIZE NOT OVER 3 3 SUB "+" AND 4 3 IFTE

OVER SIZE 1 - SUB +

NEXT

≫

IF DUP "" == THEN DROP "0" END

≫

'COMB→' STO

≪ { { 1 2 3 } { 0 1 2 3 } { 1 0 3 4 } { 1 2 0 } {0 0 0 } { 0 } { 1 1 1 } { -1 -1 -1} { -1 -2 0 -3} { -1 } }

{ } 1 3 PICK SIZE FOR j

OVER j GET COMB→ +

NEXT

SWAP DROP

≫ EVAL

{{out}}

<pre>

1: { "e1+2*e2+3*e3" "e2+2*e3+3*e4" "e1+3*e3+4*e4" "e1+2*e2" "0" "0" "e1+e2+e3" "-e1-e2-e3" "-e1-2*e2-3*e4" "-e1" }