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Show HN: I made a spreadsheet where formulas also update backwards

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Re: Show HN: I made a spreadsheet where formulas also update backwards

#21

Post by rahimnathwani »

willrshansen wrote: post #10

The first example on the main page has a formula with two variables being updated from changing one value. The immediate question I have is if I change the output, where does the extra degree of freedom come from on the inputs? Does one stay locked in place? Unclear. I am a huge fan of the concept though. It's been bugging me for years that my spreadsheet doesn't allow editing text fields after filtering and sorting…

  Does one stay locked in place? Unclear.
If you set C1=A1+B1 then, when you set a value for C1, A1 and B1 are each half of that value, even if they started off unbalanced.

Re: Show HN: I made a spreadsheet where formulas also update backwards

#23

Post by moron4hire »

b-karl wrote: post #15

In Excel you have goal seek for this functionality. I believe it does some form of numerical solving of the equation system. Good for every situation when you need to solve equations! In the context of using spreadsheets I think about solving simple financial or maybe construction/mechanical design problems where you don’t want to solve it manually or program it and a spreadsheet is a quick and useful interface.

It does not. It perturbates the variables and uses a hill-climbing algorithm.

Re: Show HN: I made a spreadsheet where formulas also update backwards

#26

Post by exe34 »

rahimnathwani wrote: post #21
willrshansen wrote: post #10

The first example on the main page has a formula with two variables being updated from changing one value. The immediate question I have is if I change the output, where does the extra degree of freedom come from on the inputs? Does one stay locked in place? Unclear. I am a huge fan of the concept though. It's been bugging me for years that my spreadsheet doesn't allow editing text fields after filtering and sorting…

Does one stay locked in place? Unclear. If you set C1=A1+B1 then, when you set a value for C1, A1 and B1 are each half of that value, even if they started off unbalanced.

I think it would be good if you could lock one of them.

Re: Show HN: I made a spreadsheet where formulas also update backwards

#27

Post by hamandcheese »

exe34 wrote: post #26
rahimnathwani wrote: post #21

Earlier quoted context omitted.

Does one stay locked in place? Unclear. If you set C1=A1+B1 then, when you set a value for C1, A1 and B1 are each half of that value, even if they started off unbalanced.

I think it would be good if you could lock one of them.

You can.

Re: Show HN: I made a spreadsheet where formulas also update backwards

#28

Post by idiotsecant »

rahimnathwani wrote: post #21
willrshansen wrote: post #10

The first example on the main page has a formula with two variables being updated from changing one value. The immediate question I have is if I change the output, where does the extra degree of freedom come from on the inputs? Does one stay locked in place? Unclear. I am a huge fan of the concept though. It's been bugging me for years that my spreadsheet doesn't allow editing text fields after filtering and sorting…

Does one stay locked in place? Unclear. If you set C1=A1+B1 then, when you set a value for C1, A1 and B1 are each half of that value, even if they started off unbalanced.

What is inputs a,b,c,d,and e are polynomial coefficients? I am hoping to get a fields medal plz respond.

Re: Show HN: I made a spreadsheet where formulas also update backwards

#29

Post by esafak »

throw310822 wrote: post #7

Hm? I don't get it. What's the point of calculating backwards non-invertible operations such as addition? Isn't the result just arbitrary?

It is for fun. Commercial products do not support this because functions are generally not invertible.
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