(Bug?) HP48 Equation Library

[Han]

(02-13-2017 01:15 AM)SlideRule Wrote:  

(02-13-2017 12:25 AM)Han Wrote:  I understood, from reading the AUR ... clearly explained in the AUR but not appearing the system involving the first formula.

Han, no insult intended. I am unaware of your level of expertise and simply sought to begin at a simple level and progress to the more complex. I do NOT have my 48 up and running (at the moment they are moth-balled).
Have you used the SUMMATION of FORCES for the individual formulas for a moment at location x from point, uniform and moment applied loads on a cantilever beam? Do you have access to ROARK or other structural formula references? The formula in the 48 manual seems to be just such a simplified summation, agreed?

BEST!
SlideRule

No offense taken and I do appreciate any and all help on the formulas. (I was merely explaining what I had quite literally just learned in the AUR.) My level of expertise is below novice when it comes to this formula. However, I am approaching this from the point of view of simply seeing a closed system of equations -- in this case, just one -- for which a variable has been declared but never used. Reading the manual has enabled me to understand what the variables stand for. But for me, this is not an attempt to actually solve anything, or use the formula for anything meaningful. On the contrary, I am merely trying understand why each variable/parameter is necessary and used (or not used) in a formula. In simplest terms, it is as if I declared (and defined the meaning of) the variables x, y, and z and my system is 2x+3y=1 and x-y=7. Anyone would wonder what the purpose of z was given that it does not appear in this closed system.

The "system" in the equation library is literally that one formula. So all on its own, the \( c \) seems extraneous to me.

I confess I know nothing about hydraulics. However, if \( c \) were somehow a value inherent/hidden in the other variables, then this would make sense. Is this perhaps what my deficiency in hydraulics knowledge is preventing me to understand?

Mark Hardman's comment about the Fanning function gives me a good place to do some research. The Fanning function seems to be where the \( \epsilon \) might be involved.

EDIT: Going back to and re-reading the chapter where the first formula, I now see a reference to Fanning -- not sure how I completely missed the large, capital letters -- but I am still stumped on the \( c \)

EDIT2: Ok, so it looks like the \( f \) in the first formula is FANNING(\(\epsilon / D, Re\) ) where the Reynolds constant is calculated as \( Re = D\cdot v_\text{avg} \cdot \rho / \mu \). The manual says that the Fanning function essentially uses two formulas depending on the whether Re is larger or smaller than 2100. So what are these two formulas?