Mathematical Geeks - help required

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geekIT

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#191123 24-Jan-2016 17:23

Hi folks. The following formula has two frequently changing variables, the '84' and '75' values.

Does anyone know of a way I could automate a solution to this equation, so that I don't have to do the whole 9-yard calculation every time?

For example, '84' will probably soon become '81' and '75' will go to '76'.

Perhaps there's a small app that'll work it?

Equation:
[66.47 + (13.75 x 84) + (5 x 175 ) - (6.76 x 75] x 1.375 =

'Those who can make you believe absurdities can make you commit atrocities.' Voltaire

'A patriot must always be ready to defend his country against his government.' Edward Abbey

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#1477855 24-Jan-2016 17:25

put it in an excel spreadsheet, with the values that change referencing cells that you edit

StarBlazer

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#1477856 24-Jan-2016 17:27

Can you not just use a spreadsheet? Put the variable values in cells and the calculation in the 3rd cell.

Procrastination eventually pays off.

doug3

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#1477933 24-Jan-2016 21:03

A good iOS app to do this is Calcility - Redefine Calculator (Lite) by JIAN FEI XU
https://appsto.re/nz/REKMM.i
It has a history section with folders and you can annotate the individual expression so you can quickly find and reuse the expression.
There is no need for all the brackets
(66.47 + 13.74 x 84 + 5 x 175 - 16.76 x 75) x 1.375 will give the same result.

toyonut

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#1477942 24-Jan-2016 21:32

#Set our variables
$var1 = Read-Host "What is variable 1?"
$var2 = Read-Host "What is variable 2?"
#write the formula out to show the variables are correct
Write-Output "Formula = (66.47 + (13.75 * $var2) + (5 * 175 ) - (6.76 * $var1) * 1.375)"
#calculate answer into $ans variable
$ans = (66.47 + (13.75 * $var2) + (5 * 175 ) - (6.76 * $var1) * 1.375)
#Write the output of the $ans variable into the console.
Write-Output "The answer is $ans"

Save that a PowerShell script then when you need it, call it up with .Directory\scriptname.ps1.

You would need to have run set-executionpolicy remotesigned at some point, else it won't run the script.

Not really serious, just a fun exercise.

*Edit* Used tab complete to set case correctly in script

Try Vultr using this link and get us both some credit:

http://www.vultr.com/?ref=7033587-3B

gzt

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#1477945 24-Jan-2016 21:54

And that marks the first time I have seen a powershell script posted on geekzone. : ).

bazzer

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#1477992 25-Jan-2016 02:28

Unless I misunderstand, your equation can be simplified to 18.90625 x [84] - 9.295 x [75] + 1294.52125 = 2185.52125

Just change the numbers in square brackets and you're all good. Relies on the distributive property of multiplication.

geekIT

2419 posts

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#1478103 25-Jan-2016 10:55

Guys, thanks for your responses, but I'm still stuck here at the bakehouse, duh. (1953 School Cert Maths = 51%)

gregmcc and StarBlazer: I'm sure your suggestions were very sensible but I've never been able to get to grips with Excel. I do have it, so if some one could post an .xls (2003) file I'd give it a try.

doug3: As far as I could see, I couldn't get the calculator without signing up for either Apple or Facebook, neither of which I'm interested in. But I think the app might be a little abstruse for me, anyway. Sorry :-(

toyonut: Like the calculator, scripting is kinda above my paygrade. Sorry :-(

bazzer: Thanks for the simplification (also doug3 for that). I wasn't aware an expression like that could be re-stated like that. If nothing else comes along (like a Cortana-ish robot for Windows 7 that asks me in a polite but seductive voice to state my variables), I'll use that method.

'Those who can make you believe absurdities can make you commit atrocities.' Voltaire

'A patriot must always be ready to defend his country against his government.' Edward Abbey

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ObidiahSlope

260 posts

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#1478119 25-Jan-2016 11:16

gzt: And that marks the first time I have seen a powershell script posted on geekzone. : ).

Yay for PowerShell, powerful and versatile. Capable in its own right and with hooks into the dotnet libraries.

Obsequious hypocrite

gregmcc

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#1478177 25-Jan-2016 12:52

1st Variable number

2nd Variable number

Answer

1399.345

=SUM(66.47+(13.75*A2)+(5*175)-(6.76*A4)*1.375)

This is the formula that goes in the box below "Answer"

Jase2985

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#1478182 25-Jan-2016 12:57

throw the formula into cell A1, substitute 84 for B1 and 75 for C1. throw 84 into cell B1 and throw 75 into cell C1. if you need to change it change the numbers in cells B1 and C1

Edit: pretty much what greg said except I went across

ObidiahSlope

260 posts

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#1478218 25-Jan-2016 13:08

Write-Output "Formula = (66.47 + (13.75 * $var2) + (5 * 175 ) - (6.76 * $var1) * 1.375)"

I have reworked the line above using Write-Host and its -NoNewline and -ForegroundColor arguments together with the semicolon command seperator to highlight the variable values.

Write-Host -NoNewline "Formula = (66.47 + (13.75 * "; Write-Host -NoNewline -ForegroundColor yellow "$var2"; Write-Host -NoNewline ") + (5 * 175 ) - (6.76 * "; Write-Host -NoNewline -ForegroundColor yellow "$var1"; Write-Host ") * 1.375)"

Obsequious hypocrite

Ouranos

118 posts

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#1478234 25-Jan-2016 13:34

gregmcc: 1st Variable number 84 2nd Variable number 75 Answer

1399.345

=SUM(66.47+(13.75*A2)+(5*175)-(6.76*A4)*1.375)

This is the formula that goes in the box below "Answer"

That spreadsheet formula has two, or possibly three, errors:

1. The SUM function is unnecessary. Effectively it says =SUM(x) which is just x. I see many people do this and I don't understood why.

2. A formula should never contain hard-coded "magic numbers". For example, what does 66.47 mean? Put each of the numbers in a cell and refer to them. Then document what each of the numbers means, where it comes from, etc.

3. The OP stated the equation as "[66.47 + (13.75 x 84) + (5 x 175 ) - (6.76 x 75] x 1.375" which has mismatched parentheses. Looking at the square brackets, I assume it is intended that the whole thing is multiplied by 1.375. If so, then =SUM(66.47+(13.75*A2)+(5*175)-(6.76*A4)*1.375) is wrong (as is the PowerShell script posted earlier). That is, does the original equation equal 2185.52125 or 1399.345?

geekIT

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#1478346 25-Jan-2016 15:38

Uh..does anyone know of a forum called DorkZone? 'Cos I think I should've posted my question there.

Think I'll just have a lie-down until my eyeballs stop spinning...

Oh, but thanks for all those erudite responses :-)

'Those who can make you believe absurdities can make you commit atrocities.' Voltaire

'A patriot must always be ready to defend his country against his government.' Edward Abbey

Dolts

214 posts

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#1478384 25-Jan-2016 16:22

Ouranos:

gregmcc: 1st Variable number 84 2nd Variable number 75 Answer

1399.345

=SUM(66.47+(13.75*A2)+(5*175)-(6.76*A4)*1.375)

This is the formula that goes in the box below "Answer"

That spreadsheet formula has two, or possibly three, errors:

1. The SUM function is unnecessary. Effectively it says =SUM(x) which is just x. I see many people do this and I don't understood why.

2. A formula should never contain hard-coded "magic numbers". For example, what does 66.47 mean? Put each of the numbers in a cell and refer to them. Then document what each of the numbers means, where it comes from, etc.

3. The OP stated the equation as "[66.47 + (13.75 x 84) + (5 x 175 ) - (6.76 x 75] x 1.375" which has mismatched parentheses. Looking at the square brackets, I assume it is intended that the whole thing is multiplied by 1.375. If so, then =SUM(66.47+(13.75*A2)+(5*175)-(6.76*A4)*1.375) is wrong (as is the PowerShell script posted earlier). That is, does the original equation equal 2185.52125 or 1399.345?

If you can state if 2185.52125 or 1399.345 is the correct answer that you need, I have written a small app that gives the answer 1399.345

gzt

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#1478416 25-Jan-2016 16:39

geekIT: Does anyone know of a way I could automate a solution to this equation, so that I don't have to do the whole 9-yard calculation every time?

Do you have a gmail account? This could be set easily by someone here as a form to input data from a web page.

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