- Customised Solutions For The Tanker IndustrySN's Goalseek Premium V1.08

The Grey Background is a Watt-Reduction Theme.  Every milli-Watt counts.

Reduce....>>  Reuse ...>> Recycle ...>> Rethink...>> Repair  






Where to Advertise?

World Tourist Attractions

Best Place To Advertise



Buy BigLoveAsia 

Universal Prayer - Connecting The Top 40, A Directory Service





Executive Overview

An Analysis of an Algorithm Improvement for - Excel's GoalSeek Function

This document analyzes the capabilities of the SNGSP program compared to Microsoft Excel's existing GoalSeek algorithm and its stand-in for enhanced goalseeking 'Solver'. A compelling case is developed for leveraging SNGSP in future versions of Microsoft Excel.

The Purpose of Excel's Goal Seek

Goal Seek is part of a suite of commands in Excel that are used to conduct 'what-if' analysis. This type of analysis consists of a process where the user changes values in a single selected cell to determine the impact of other formulas in a worksheet. This approach is particularly useful when the user knows the expected result of a formula, but does not know the initial input starting value to obtain that result. One example involves loans and interest rates in an amortization table, whereby the user can determine the amount of payments. The Excel Goal Seek algorithm can vary the result in only one specific cell, until a formula that depends on that's dependent on that cell returns the result desired by the user.

<< Top >>

Excel's GoalSeek limitations

GoalSeek is capable of solving a target cell value by changing only one cell. It is also susceptible to the limitations of finite precision computer arithmetic.

Competitive products

Lotus 123's BackSolver has a largely superior algorithm. It can solve for required target cell values by changing values in a range of contiguous cells. The drawbacks of their algorithm are that changing cells are either all incremented or all decremented irrespective of the natural relationship of the individual cells w.r.t. the target cell. Further, the changing cells should be contiguous and therefore, naturally on one sheet.          

<< Top >>

SNGSP Capability Improvements

- SNGSP can work with multiple variable cells, in multiples of sheets in multiples of open workbooks. Up to 64000 cells in multiple ranges may be incorporated into the problem - but that figure can be increased or lowered to suit business strategy. Those cells, if selected, but do not relate to the target cell by formulae or functions, will be automatically ignored. Upper and lower bounds may be set individually for each range. Solver cannot work with multiple worksheets/workbooks.

- SNGSP can work with protected workbooks, Solver cannot.

- SNGSP can/will alter its internal precision differently for each variable cell in an effort to find a solution (in case the user has incorporated the Round, etc. functions in his/her workbook).

- SNGSP does not get bogged down if the starting values are such that the "set up" sub-routine does not detect a change in target cell value. For example: See the image in and look at the Measured Ull column. This column represents the ullage of the respective tank. (Ullage is a measure of the empty space above the liquid cargo in a tank - Total tank height less the height (sounding) of the cargo). The ullage for empty tank is usually an odd figure like 22.068 or 21.567, etc. The users of the program will not write this cumbersome figure to indicate empty tank, they will adopt a rule such as to enter 23 in tanks that are empty. With 23 in the measured ullage column, the volume, etc. will be zero. SNGSP will not be bogged down by this, as it will progressively increase its internal precision in an effort to detect and measure a change. Solver cannot work if start values do not change with changes as per its setup computing sub-routines.

- SNGSP can use the value of a referenced cell for the set-cell value. As the value in the referenced cell changes with change of the variable cells, so will the problem target value change, until an equilibrium is reached. Solver cannot.  

-  SNGSP uses extensive branching routines to overcome non-linear hitches and limitations of finite precision computer arithmetic. Solver has more limitations in this respect.         

- As computing progresses, should certain cells reach their threshold for upper or lower bounds or if they tend to cause the introduction of an error situation (#div0, #num, etc), those cells are blocked at their last acceptable value and computing continues with the remaining cells. Solver stops at the first encountered error.

- SNGSP is not an optimizing tool and so cannot compute for optimizing scenario where minimum, maximum and a set of constraints are set. Conversely, the optimizing tool, Solver as shipped free with Excel has a host of limitations and cannot backsolve/goalseek as effectively as SNGSP.
- SNGSP may be called programmatically from the user's VBE but limited to 10 ranges. (This feature is under further development).

Please check out this article on Excel GoalSeek and Solver limitations. SNGSP overcomes any of these with start values up to 120,000.          

Current and potential future uses of Excel with SNGSP

SNGSP's algorithms are called programmatically in cargo related spreadsheet based software written by its author for some tank vessels in various shipping companies.  All Excel users are potential customers for the spreadsheet based solutions that has as one of it features, backsolving (premium goalseeking).

All those who have changed over from Lotus-123 for various reasons but sorely miss the BackSolve feature but cannot do much about it will welcome this add-in.


SNGSP is a tool that should interest any user who knows the result he/she is looking for but does not know the values in the changing cells required to achieve this. The more complicated the project, including a tendency for the project to go into a 'circular' computation, enhances to evidence of the need of such a tool.

SNGSP can be improved upon in collaboration with Redmond.

     Home                                Back                                                                   << Top >>

Can't find' Do a custom search here   

                  Contact Us       

©Copyright Sovereign Newzealand® 1999-2013                      Terms & Conditions / Privacy Statement

Advertise With Us