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All, I have now been trying to use the MatLab code in C++, I get a result, a subsequent iterations change the values, I believe the result is still in correct-- perhaps not, I will check.

...

Changed the '<' sign as suggested and the result is the same: -1 for the friction coefficient.


//TURBULENT
if (rnum > 4000) {

do
{
...

I have tried your method and came up with:


do
{
tpfc = pow ( -2 * log10 (rrough / 3.7 + 2.51 / ( rnum * sqrt (tpfc2 + 1e - 300 ))), -2);
}
...

Indeed you are all correct.



I would prefer a tolerance of 1-E6. But am still unsure as to how to make that happen. The goal of the formula is to use iteration to solve for the factor (f) until...

So I would need to use a "Do" statement?

From MSDN:

do
{
tpfc = pow ( -2 * log10 (rrough / 3.7 + 2.51 / ( rnum * sqrt (tpfc2 + 1e - 300 ))), -2);;
} while (tpfc = tpfc2);

Interesting, it looks like I have done a bunch of defining variables when that was un-needed. Just another thing to put down for the ol'learning curve.

Now when you mention a big-loop, I am...

Howdy all,

I just started programming some 1 days ago, I have the program complete except for the following problem-- iteration. I consider myself pretty engineering savy when it comes to Excel...