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Typesetting alias in rtables...

vv 14132 Maple 2017
matrix typesetting
October 04 2017
1 1


 

alias in rtables does not work when typesetting=extended (default in Maple 2017)

> 

restart;
> 

alias(alpha=RootOf(z^3+z+1,z));

alpha

 (1)
> 

L:=simplify([seq(alpha^k,k=0..5)]);

[1, alpha, alpha^2, -alpha-1, -alpha*(alpha+1), -alpha^2+alpha+1]

 (2)
> 

V:=convert(L,Vector);

_rtable[18446744074335181870]

 (3)
> 

interface(typesetting=standard);

extended

 (4)
> 

V;

7275930162710271107275012117273962706

 (5)
> 

 

unames() in extended typesetting bug...

vv 14132 Maple 2017
typesetting unames
September 26 2017
1 1

unames()   produces an error  in extended typsetting mode (the default in Maple 2017)  after any output.

> 

#interface(typesetting=standard);
> 

restart;
> 

interface(typesetting=extended);

extended

 (1)
> 

unames();

Error, invalid input: Typeset:-Kernel expects an equation for keyword parameter numericformatting

  

` `

  

Error, unexpected result from Typesetting

  
> 

 

displayprecision and typesetting...

vv 14132 Maple
typesetting displayprecision
June 25 2017
1 0

According to the help page:
interface(displayprecision=n)
sets the number of decimal places to be displayed to n.
But this is true only if interface(typesetting=extended).
For interface(typesetting=standard),  n represents the number of decimal places after the decimal point.
Is there any reason for this decision?

restart;
x:=123.456789012345:
interface(displayprecision=4):
interface(typesetting=standard): x;
                        123.4568
interface(typesetting=extended): x;
                        123.5

 

 

A simple limit - bug...

vv 14132 Maple
limit
May 26 2017
0 3

L := sum( 1/ln(k), k=2..n ) * ln(n)/n;
        
limit(L, n=infinity);
                               0
# Should be 1

Just curious: in Maple 2017, is it OK?

 

TravelingSalesman - speed...

vv 14132 Maple
iterator travelling-salesman-problem
May 13 2017
1 4


 

How is it possible that  GraphTheory:-TravelingSalesman  
is much slower than a simple brute-force solution?

 

> 

restart;
> 

n:=10:
> 

A:=Matrix(n, (i,j)->`if`(i=j,0,n*(n-i)^4+2*j+(n-i)^2+j^3)):A[1,2]:=100*n^3:A;

Matrix([[0, 100000, 65724, 65763, 65826, 65919, 66048, 66219, 66438, 66711], [41027, 0, 41057, 41096, 41159, 41252, 41381, 41552, 41771, 42044], [24062, 24071, 0, 24131, 24194, 24287, 24416, 24587, 24806, 25079], [12999, 13008, 13029, 0, 13131, 13224, 13353, 13524, 13743, 14016], [6278, 6287, 6308, 6347, 0, 6503, 6632, 6803, 7022, 7295], [2579, 2588, 2609, 2648, 2711, 0, 2933, 3104, 3323, 3596], [822, 831, 852, 891, 954, 1047, 0, 1347, 1566, 1839], [167, 176, 197, 236, 299, 392, 521, 0, 911, 1184], [14, 23, 44, 83, 146, 239, 368, 539, 0, 1031], [3, 12, 33, 72, 135, 228, 357, 528, 747, 0]])

 (1)
> 

with(GraphTheory):
> 

G:=Graph(A);

GRAPHLN(directed, weighted, [1, 2, 3, 4, 5, 6, 7, 8, 9, 10], Array(%id = 18446744074326770022), `GRAPHLN/table/1`, Matrix(%id = 18446744074326769782))

 (2)
> 

t:=time[real]():
TravelingSalesman(G);
'time'=time[real]()-t;

156750, [1, 3, 2, 4, 5, 6, 7, 8, 9, 10, 1]

  

time = 36.410

 (3)
> 

############### brute-force #############
> 

t:=time[real]():
P:=Iterator:-Permute([seq(2..n)]):
cmin:=infinity: ord:=<"none">:
for  v in P do
  f:=add(A[v[k],v[k+1]],k=1..n-2) + A[1,v[1]]+A[v[n-1],1];
  if f<cmin then cmin:=f; ord:=copy(v) fi;
od:
cmin,[1, entries(ord,'nolist',indexorder),1];
'time'=time[real]()-t;

156750, [1, 3, 2, 4, 5, 6, 7, 8, 9, 10, 1]

  

time = 1.715

 (4)
> 

# And for n=11 I had to interrupt TravelingSalesman;
# brute-force still works for n=12.


 

Download TravelingSalesman-test.mw

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