## 894 Reputation

17 years, 323 days

## Predict Perfect...

Maple 2018

Hi

Initially I tried to find pemutations of 1..9, ie [[1,2,3],[4,5,6],[7,8,9]],[[1,2,4],[3,5,6],[7,8,9]],...etc, But maybe not all of them?

I wonder if someone out there can change my code to reflect the following:

1/According to the pdf excerpt, there are a total of 199 unique sums, the smallest sum is 774 and the largest 2556.(From displaying 280 outcomes, the code got the 774).

2/Show which sums have the greatest probability (specifically, 1566, 1575, 1638, 1656, 1674, 1692, 1755, and 1764, each of which can be shown with effort to have a 3/280, or 1.07%, probability – the calculations to determine this probability is a brute-force computation, and requires enumerating all outcomes of the sample space within a computational software package). We then finally reveal the prediction, which of course is correct..(I don't get it)

predict_perfect.mw

## Pls help me find the law...

Maple 2018

Hi

I am trying to find how it calculates how much solar will be exported back to the grid. I thought this could only be estimated  empirically, but apparently not.

Anyway, it depends on three factors, power consumption, power installed, and average hours of sun per day, or hours per day as a function of time of year. For C=4.5kWh/day and S=5kW and H=4 sun hrs per day, means 90% will be exported back to the grid Y. So Y(C,S,H)= a closed form expression.

How to guess the fuction? I tried array interpolation for a numeric solution, but it complains: independent coordinates must be sorted in increasing order

law.mw

## Select elements of list wrt criteria...

Maple 2018

Hiya

from this

>with(combinat):
>A:=choose([CPC__h, SIZE__h,CPC__m, SIZE__m,CPC__l, SIZE__l],2):

where h denotes high, m=medium, l=low

I want to select CPC and SIZE all the combinations w.r.t h, m and l

[[CPC__h, SIZE__h], [CPC__h, SIZE__l], [CPC__h, SIZE__m], [CPC__l, SIZE__h], [CPC__l, SIZE__l], [CPC__l, SIZE__m], [CPC__m, SIZE__h], [CPC__m, SIZE__l], [CPC__m, SIZE__m]]

>nops(A)-3

9

I want to apply the methodology to
choose([CPC__h, SIZE__h, SH__h,CPC__m, SIZE__m, SH__m,CPC__l, SIZE__l, SH__l],3)

## Differential forward quote...

Maple 2018

This may seem a bit trivial, but I prefer f'(x) to writing diff(f(x),x) in 1D input. How to achieve?

differential.mw

 (1)

In Document mode, this works fine.

 (2)

 (3)

But I mainly use Worksheet (1D) mode, and I can't seem to acheve the same, without using diff(f(x),x)

f:x->x^2

 (4)

f'(x)

## LambertW analogous function in MS Excel...

Maple 2018

Hello

I have an expression which invokes the LambertW function.

LambertW(-ln(1+i)*EP*p*(1+i)^(-(365*EP*hr*kw*p+SC*i)/(365*FIT*hr*i*kw*(-1+p)))/(FIT*i*(-1+p)))

I was trying to import this expression into Excel, but my version doesn't have LambertW.

Does someone know an analagous function in a form Excel can compute?

According to wiki The Lambert W relation cannot be expressed in terms of elementary functions.

I have gotten around the problem using Newton-Raphson method, but it takes a few cells to converge....

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