[Programming] Condition problem

Question

[Programming] Condition problem

rrozz (Chemical)

(OP)

7 Jul 11 10:33

Hi again,

The enclosed program selects the most appropriate pipe stub from a standard. Although the program works, it returns bad results.

For specified dimensions of pipe, it doesnt find the anticipated result and iterates till it runs out of arguments.

The condition d.2oprz+2*δ.2oprz=(boolean eq.)=d.zkróćca[k*mm for specified dimensions should be fulfilled at 11th iteration, but the loop does not exits.

Can any one help?

IRstuff (Aerospace) · Answer 1 · 2011-07-07 13:03:39

I don't know how much math or programming you took in school, but surely, you realize that computers do not store decimal values exactly?

Any decimal value you enter is stored as a binary floating point number per IEEE standard.  Therefore, unless you are using only integers, it would be exceeding unlikely to get an exact match for two seemingly identical decimal values.  If you do the actual math, you'll see that the values differ by 2.776E-17 mm.

Read "Lookup Functions" in the help files for how Mathcad does it for its internal lookup functions.  You need to determine a tolerance and program accordingly.

TTFN

FAQ731-376: Eng-Tips.com Forum Policies
Chinese prisoner wins Nobel Peace Prize

rrozz (Chemical) · Answer 2 · 2011-07-07 19:19:45

Thanks for your feedback.
Your sarcasm is unnecessary, even if my knowleadge is bad.

IRstuff (Aerospace) · Answer 3 · 2011-07-08 16:50:33

Huh?

TTFN

FAQ731-376: Eng-Tips.com Forum Policies
Chinese prisoner wins Nobel Peace Prize

CRG (Mechanical) · Answer 4 · 2011-07-11 21:13:25

rrozz, your comment about sarcasm is no way to say thank you very much for someone's help. Gee, you ask a technical question on a forum and 3.5 hours later you get a relevant answer. The answer was prefaced with a statement that pretty much explained that he thought you already knew, but just in case, he went ahead to explain a possible cause anyways. Not everyone gets/deserves a trophy for participation.

Come Join Us!

Posting Guidelines

[Programming] Condition problem