Return to index: [Subject] [Thread] [Date] [Author]

RE: Excel Question

[Subject Prev][Subject Next][Thread Prev][Thread Next]
One way is to tabularize the function's output and use 'dmax' to find the
maximum value.
JPRiley

-----Original Message-----
From: Gerard Madden [mailto:GMadden(--nospam--at)mplusl.com]
Sent: Friday, July 13, 2001 7:29 PM
To: seaint(--nospam--at)seaint.org
Subject: Excel Question


This is for all you PHD's  :>)

I using the SOLVER tool on Excel to perform iterations to find a worst case
value. The value is dependent on a number of variables in the spreadsheet.

What I am asking it to do is to change the value of one cell until another
reaches its maximum value. In this case, I am asking for an angle. from 0 to
180 degrees, that gives me maximum force on a group of bolts.

What the problem is, as explained to me by a PHD who sits next to me, is
that the curve for the function can have several peaks and valleys. The
SOLVER tool built into the program searches for a LOCAL MAXIMUM from the
initial point entered in the cell.

For example, if I have a function that has 3 peaks and 4 valleys

Valley 1 = 0 degrees
Peak 1 = 35 degrees
Valley 2 = 50 degrees
Peak 2 = 80 degrees
Valley 3 = 115 degrees
Peak 3 = 125 degrees    = CORRECT ANSWER
Valley 4 = 180 degrees

Assuming straight lines between peaks and valleys in the function (for
simplifying my example)

Peak 3 gives me the worst case force and is the true correct answer. The
solver will only select Peak 3 if my initial input value is Greater than
Valley 3 and Less than Valley 4. What I want is to set the cell to zero and
have it go through the entire range of values, from 0 to 180, and spit out
the right number

My PhD colleague says there are more sophisticated solver modules.

My questions are ... does anyone have any hints or know of a place I could
download a solver that would do what I want?

TIA

-Gerard



Gerard Madden, P.E.
Civil Engineer

Middlebrook + Louie, Structural Engineers
71 Stevenson Street, Suite 2100
San Francisco, CA 94105
Tel: 415.546.4900
Fax: 415.974.3680
Email: gmadden(--nospam--at)mplusl.com
Web: www.mplusl.com


*
*   This email was sent to you via Structural Engineers
*   Association of Southern California (SEAOSC) server. To
*   subscribe (no fee) or UnSubscribe, please go to:
*
*   http://www.seaint.org/sealist1.asp
*
*   Questions to seaint-ad(--nospam--at)seaint.org. Remember, any email you
*   send to the list is public domain and may be re-posted
*   without your permission. Make sure you visit our web
*   site at: http://www.seaint.org


* 
*   This email was sent to you via Structural Engineers 
*   Association of Southern California (SEAOSC) server. To 
*   subscribe (no fee) or UnSubscribe, please go to:
*
*   http://www.seaint.org/sealist1.asp
*
*   Questions to seaint-ad(--nospam--at)seaint.org. Remember, any email you 
*   send to the list is public domain and may be re-posted 
*   without your permission. Make sure you visit our web 
*   site at: http://www.seaint.org