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Question: indexed versus symbol

Question:indexed versus symbol

Harry Garst 234 Maple
indexed
February 24 2022
3

I don't know how to fix this. What's wrong? Is there an alternative way to include underscores in a cat command?

``

> 

restart; with(LinearAlgebra)
> 

komb := proc (n::integer, m::integer) local L, a, j; L := [seq(cat(a, "__", j, ",", j), j = 1 .. n)]; add(mul(k), `in`(k, combinat:-choose(L, m))); return % end proc

proc (n::integer, m::integer) local L, a, j, k; L := [seq(cat(a, "__", j, ",", j), j = 1 .. n)]; add(mul(k), `in`(k, combinat:-choose(L, m))); return % end proc

 (1)
> 

komb(5, 5)

`a__1,1`*`a__2,2`*`a__3,3`*`a__4,4`*`a__5,5`

 (2)
> 

whattype(`a__1,1`)

symbol

 (3)
> 

A := Matrix(5, 5, shape = diagonal, symbol = a)

Matrix(%id = 36893489895174306860)

 (4)
> 

abs(A)

a[1, 1]*a[2, 2]*a[3, 3]*a[4, 4]*a[5, 5]

 (5)
> 

whattype(a[1, 1])

indexed

 (6)
> 

simplify(komb(5, 5)-abs(A))

`a__1,1`*`a__2,2`*`a__3,3`*`a__4,4`*`a__5,5`-a[1, 1]*a[2, 2]*a[3, 3]*a[4, 4]*a[5, 5]

 (7)

``

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