Your project and last post raise several issues.

I am not familiar with Gnu Octave. And why so long to get the output transferred to Excel. Are you using clipboard to transfer? Once in Excel VBA could again be helpful in reformatting the data.

There is a recent post of a list of Excel resources by hiker95. Hang around this forum and you will soon find helpful info like this.

http://www.mrexcel.com/forum/excel-...anging-columns-rows-advanced.html#post3925232
The list is long. If you prefer book over video, one book like Walkenbach's power programming with Excel book may be enough.

Excel comes with two help systems, one on the sheet, and a different one from the code window.

Convergence may not always happen, or could different starting numbers result in converging to different result? You may have to test to find out.

What exactly are stock quantities?

How easy is it to learn VBA depends. VBA is similar to some other programming. It has standard variable types, many functions corresponding to the worksheet functions, simple and array variables, loops. If you are already familiar with these concepts it would go much faster learning to transform cell type formulas into code. Some people revel in getting Cell Formulas to work. But this approach is not always practical.

There are various debugging techniques for VBA code explained in the references. Some may use one simple technique, while others may use a variety of techniques. Debugging Cell Formulas or VBA code involves first spotting a problem, then figuring out what is wrong, and how to fix it. It should get easier and faster with practice.

With such a project with no answer key how do you test it? Organization factors such as compartmentalization into modular parts factor into design. Start simple and add functionality. Could a cell formula and code version be built and compared, or an Excel and Gnu Octave version? With complex climate modeling, different models can be compared. What value is the result unless there is confidence it works as planned and how is that demonstrated? Similarly a math problem can often be solved by two different methods to show the same answer. So if you ask if it is worth it to learn another method these issues come to mind. Without some kind of testing or verification or validation you may just be building a house of cards.

Other books, not specifically on Excel, may also give you ideas on approaching complex projects.

The pragmatic programmer by Andrew Hunt published 1999.

This book discusses issues such as building a prototype, and adding complexity.