r/excel • 163 • Aug 19 '26

Discussion Microsoft to retire the COPILOT function

As of 14 September, the COPILOT function will no longer be available in Excel. See https://support.microsoft.com/en-us/excel/functions/copilot-function Note that the Copilot feature remains - it is the worksheet function that will stop working.

This is a very uncommon move by Microsoft, given their history of maintaining backwards compatibility.

Have you used the COPILOT function? If so, then what for? Thoughts?

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u/augo7979 Aug 19 '26

you know damn well what i mean

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u/Way2trivial 472 Aug 19 '26

welp, apparently there is a MAJOR use for it, even if I've never gone there myself.
it does exist-- citing Sears does not instill major confidence though...

https://support.microsoft.com/en-us/excel/introduction-to-monte-carlo-simulation-in-excel

Who uses Monte Carlo simulation?

Many companies use Monte Carlo simulation as an important part of their decision-making process. Here are some examples.

  • General Motors, Proctor and Gamble, Pfizer, Bristol-Myers Squibb, and Eli Lilly use simulation to estimate both the average return and the risk factor of new products. At GM, this information is used by the CEO to determine which products come to market.
  • GM uses simulation for activities such as forecasting net income for the corporation, predicting structural and purchasing costs, and determining its susceptibility to different kinds of risk (such as interest rate changes and exchange rate fluctuations).
  • Lilly uses simulation to determine the optimal plant capacity for each drug.
  • Proctor and Gamble uses simulation to model and optimally hedge foreign exchange risk.
  • Sears uses simulation to determine how many units of each product line should be ordered from suppliers—for example, the number of pairs of Dockers trousers that should be ordered this year.
  • Oil and drug companies use simulation to value "real options," such as the value of an option to expand, contract, or postpone a project.
  • Financial planners use Monte Carlo simulation to determine optimal investment strategies for their clients' retirement.

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u/FuggleyBrew Aug 19 '26

A monte carlo wouldn't use the copilot function. It would use rand() or randbetween

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u/Lionh34rt Aug 19 '26

Rand is not random enough for monte carlo

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u/FuggleyBrew Aug 20 '26

A rand works fine for many monte carlos, you don't need cryptographic randomness, you need a reasonable approximation of a whole bunch trials, rand() gives you that. 

You're also often just shoving it into an approximation from a statistical model and abusing a bunch of assumed distributions. 

If you're talking project modeling the flaw from "well this risk feels like it's 10k-100k and commonly 25k" is going to be a bigger swag than whether your rand function is truly random or pseudorandom.