18 years, 6 days

## How to append [i] to each element of the...

Maple 2018

This is probably a silly question, but...

given

GST := AE+AI-ANB-AR-CP

how do i append [i] to each element of the list so I get

AE[i]+AI[i]-ANB[i]-AR[i]-CP[i]

this nearly gets it

(GST@`[]`)~(i);

## How to assign new unit rather than defau...

Maple

I was trying some calculations for a solar installation.

4.9kW system. 3.5 h sun/day.  \$0.27/kWh

restart:
with(Units:-Standard):
4.9*Unit(kW)*3.5*Unit(h/day)

714.583333333333*Unit('W')

but I want it to output 17.15 kWh/day

I looked up previous questions, and got this rather convoluted solution:

restart:
Units[UseSystem]( NewSI );
combine( 4.9*Unit(kW)*3.5*Unit(h/day), units );

17.15*Unit('kWh'/'d')

## How to do recursion to model population ...

Maple 2018

Hello

I found this paper.

I'm not sure if the population after 1 year is correct.

I wanted to get the formula from rsolve. But i have incorrorectly formulated the sum by day and the total.

Rattus_recursion.mw

## How to remove zeros from output?...

Maple 17

Hello

If 0 occurs in the first element, I want to remove the list containing zero and the associated number.

example

p := [[[0, 5], [3, 10], [1, 20], [0, 50]], [[2, 5], [0, 10], [2, 20], [0, 50]]]

after processing:

[[[3, 10], [1, 20]], [[2, 5], [2, 20]]]

I tried in vain...

select(i -> (subs(p,p[1,i,1])>0), [\$1..nops(p)]);

## Update standings...

Maple 2017

update_standings_ELO_draw.mw

This latest question involves ELO, which is used to rate chess players (and other sports).

The difference between the previous (win-loss) system and ELO is the allowance for a third option, a draw. Carl coded the previous rating system, and I have tried to alter it.

See code for ELO procedure.

Adding a D to the third field, gets the result I want.

ELO(Record(rating= 2400),Record(rating= 2000),D)

Adding anything other than D to the third field means the first player defeats the second.

My preference would be to leave nothing in this third field to signify this (but I don't know if this is possible).

The main problem is getting the bulk processing to work (for a series of matches...)

See Update procedure.

I have this flawed notation:

Games:= [[Tom_C, David_J, D],[David_J, Tom_C]]: #Tom_C drew David_J then David_J defeats Tom_C.

Hope someone can help.

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