Equation into Excel using PEMDAS

[Spasmodic]

Hello All,

I am trying to put formula A13 into Excel but am not sure how to write it using PEMDAS. Any help would be appreciated as I can just plug in the numbers for things like Pmax and etc. Thank you in advance.

http://download.lww.com/wolterskluw.../MSS_44_2_2011_12_14_SAMOZINO_202175_SDC1.pdf

 

[shg]

=(-(g^6) * hpo^6 - 18 * g^3 * Pmax^2 -54 * hpo^4 * Pmax^4 + 6*SQRT(3) * SQRT(1*g^3 * hpo^9 * Pmax^6 + 27 * hpo^8 * Pmax^8))^1/3

 

[shg]

Oops:

=(-(g^6) * hpo^6 - 18 * g^3 * Pmax^2 - 54 * hpo^4 * Pmax^4 + 6 * SQRT(3) * SQRT(2 * g^3 * hpo^9 * Pmax^6 + 27 * hpo^8 * Pmax^8))^(1/3)

 

[Spasmodic]

Thanks you. I will give this a try and see how it works. If you don't mind, how would you do something a little more complicated like equation A12. Now that I have the Z(Pmax,hpo) formula, I would just select the cell that it's in but how would you write A12 using PEMDAS?

 

[shg]

How about you try and I'll review?

 

[Spasmodic]

A12 = (-g(^2)/3*Pmax)) - ((-(g^4*hpo^4)-12*g*hpo^3*Pmax^2)/3*hpo^2*Pmax*Z(Pmax,hpo)) - (Z(Pmax,hpo)/3*hpo^2*Pmax) ?

 

[shg]

Does it work? Plug in some numbers (ideally, some for which you know the result) and watch it evaluate using the Evaluate Formula button on the Formula Auditing toolbar.

Note that Z is a function defined by formula A13, so that should just be a cell reference.

 

[Spasmodic]

I tried it again with (-(g^2)/3*Pmax)) - ((-(g^4*hpo^4)-12*g*hpo^3*Pmax^2)/3*hpo^2*Pmax*Z(Pmax,hpo)) - (Z(Pmax,hpo)/3*hpo^2*Pmax) but it keeps giving me the wrong number. Been trying this for about a week now and it is getting really frustrating.

 

[shg]

Unless you've written a user-defined function named Z, that won't give you anything but a #NAME? error.

This

=(-(g^2)/3*Pmax)

should be

=(-(g^2)/(3*Pmax))

because the Pmax is in the denominator.

Excel's precedence of operators is

– (Parentheses)
– Reference (i.e., the colon in A1:B1, the comma in (A1, B1), and the space in (B2:C5 B4:E6))
– Unary Negation (=-3^2 returns 9, not -9)
– Percentage
– Exponentiation
– Multiplication & Division
– Addition & Subtraction
– Catenation (A1 & B1)
– Comparison
– Left to Right among equivalents

So 2/3*5 is is the same as 5*2/3. If you want the 5 in the denominator you need parens:

2/(3*5)

 

[Spasmodic]

Well I used the Z equation in another cell and just referenced it in the other equation but last week when I tried it, it gave me a ridiculously large number like 2 billion when it should be in the in the negative 1000 range. Using the equation I tried again, it gave me a positive number but it was only in the teens so I know the equation I tried was wrong. Never got the #name error though.