Coding math with VB6

[oswaler]

Thank you, I would like to have a look at the code if you don't mind.

A follow up: In the program I'm writing I'm having the computer do a numerical integration of the type of function listed above. My method right now is to do a simple Riemann sum using a For Next loop. I find I can get better accuracy by using more segments so that for instance I could have the loop run 2.1 billion times and sum up the tiny areas. This takes 33 minutes to do an integration that I can do in my head in 30 sec. Is there a faster mechanism for running the same kind of Riemann sum the same number of times but in much less time?

Thanks - Eric

[Raedwulf]

Ahh i see what you are doing, I can't guarantee it will be fast, because parsing a expression real time is slow. Usually you would need an engine to convert the function into machine code (i.e. compile real time once) and then just use the function over and over again.
I'll post the evaluator, but it may be above your level of coding to understand:

I'll just outline what you need to do:

You need the following modules added to your project:
MPostfixEvaluator.bas
MAssemblyThunks.bas

When you want to Calculate Something:

Dim tRPN(0 To 49) As RPN_EXPRESSION_ITEM
Dim sInput As String
Dim lCount as Long
Dim rAnswer as Double

sInput = "2 + 2"

lCount = ConvertToPostfixRPN(sInput, tRPN)
rAnswer = EvaluateRPNExpressionDouble(tRPN, lCount)

txtAnswer.Text = rAnswer

Before you get carried away, you can't use sInput = "x + 2", because I haven't programmed in support for variables.

Note: This will certainly be slower than your current method, and I believe, Reimann's numerical integration is slow anyway .....so maybe look at the
Simpon's Rule

Cheers.