Optimization

[ptc-4510012]

I have a range of values that is entered in the program. in this case CL and HL, which are the height of a telephone pole.

here are the equations i have to work with.

h=0.001*S^alpha + CL

c=C1+2*h^beta

S=L/(N-1)

D=N/NP

and CT=c*N+NW(1 and 2)*C2*D

aplha,CL,C1, C2, beta, NW1, NW2, L, HM, HL, NP are all variables entered at the beginning of the program.

i need to find the lowest total cost (CT) with respect to the height when it is between CL and HL for NW1 and then between HL and HM for NW2. HL is the deciding point between a crew of NW1 for below HL, and above is NW2.

I attached a copy of the assignment and tomorrow will attach a copy of what i have so far.

[VladimirN]

Please attach your Mathcad worksheet to the message.

[ptc-4510012]

here is is, i still have not added units. having trouble getting them to work corretly.

[ptc-4510012]

basically what i need to do is evaluate an equation over a range, from CL to HL and find the lowest cost.

i found an error in one of my equations

[Fred_Kohlhepp · Accepted solution]

Try this:

[ptc-4510012]

Fred that helps alot, i had to make a few changes to get it correct. the only issue is i need it set up so i can change the input paramaters for different situations.

thanks again for the help
Case

edit, i uploaded the changes i made and "think" it will work, the "h" equation you made is amazing.

i also attached a copy of the correct answers from hand calculations.

Case

[Fred_Kohlhepp]

You have a block where you assign numbers to the parameters. If you change these values the sheet will calculate the new minimum cost and report the associated values.

[ptc-4510012]

is there anyway you can explain what the h equation does and the equations below it?

[ptc-4510012]

for the HG statement

what does the epsilon mean?

im trying to understand what "for hh E HL..HM" line is trying to do.

[Ian1]

OK, so this is a bit of nit picking - but the number of poles is not the lenght/span - you need a pole at each end

it is lenght/span + 1

[Fred_Kohlhepp]

You're right! Not nit-picking! 🙂

[ptc-4510012]

for some reason Fred when I change the number of workers the answer is not correct.

[Fred_Kohlhepp]

Case Bonebrake wrote:

for some reason Fred when I change the number of workers the answer is not correct.

Attached is a non-working explaination sheet. (I feel like I'm doing your work for you.)

Post your example of "not working".

When I run your EXCEL number through the sheet, I get agreement. But I can't see the math behind your EXCEL sheet.

[ptc-4510012]

i really do appreciate the help, i have over 40 hrs into this project.

[Fred_Kohlhepp]

You've got a problem!

[ptc-4510012]

for some reason its only looking between HL and HM

[Fred_Kohlhepp]

Because that's all you're searching through in HG:

[ptc-4510012]

when i tried to change the HL it didnt like it. trying to determine why now. thanks again for taking the time to help and explain things.

[ptc-4510012]

when i change HL to CL, i get the "this function is undefined at one or more of the specified points".

i did change the hh at the top to hh:=CL..HM

[Fred_Kohlhepp]

Your EXCEL sheet still has no math.

Putting these values through the Mathcad sheet attached:

[ptc-4510012]

the excel sheet was made after doing all the hand caluclations, or a program i wrote in mathcad. would have been alot simpler if i had written it in mathcad.

[ptc-4510012]

i think i figured it out, when you change the HL to CL, it shows an error because the height equation has CL in it, so it wont work. i added a new variable, CR:=CL+1 to get around this. thanks again for all the help Fred.

[ptc-4510012]

here is my final program.

[Fred_Kohlhepp]

Looks good!

Let me know what grade we get!