question for math wizards

[mister_e]

SQR(mmH2O)*(504/65)

SQR(mmH2O)*(1543/199)

SQR(mmH2O)*(2551/329)

SQR(mmH2O)*(31116/4013)

Hint: Use MiscEl

Careful with the math overflow

[aajgss]

Awesome stuff Steve

Thanks for your help

aajgss

ps not sure what you mean by MiscE?

[mackrackit]

Give this a try...
MiscEL

[aajgss]

Got It!

Thought it was a ! and not an l - old eyes no glasses. Often get told I need them - maybe I do


Thanks
aajgss

[mackrackit]

Got It!

Thought it was a ! and not an l - old eyes no glasses. Often get told I need them - maybe I do


Thanks
aajgss

I know what you mean... without mine I walk into walls .. try stairs with a new pair of bifocals

[mister_e]

I'm sure in the same boat... without mine I can't even say if it's an elephant ... or a supermarket

[Archangel]

Got It!

Thought it was a ! and not an l - old eyes no glasses. Often get told I need them - maybe I do


Thanks
aajgss

You mean you tried to read that text and type it ? !!!

Thank Jobs / Gates / Linus for copy/paste !

[aajgss]

Ok,

Lets forget I said the first bits easy!!!

Instead of converting to mmH2O and then converting that to Knots, I decided to go straight from ADC counts to Knots.

So the equation comes out to be (SQR(ADC Counts))* ( 484/79).

Excel comes up with the correct answer. for 1 ADC count the result comes out at 6.1266 knots. Doing the same calculation in a PIC the result is 6 knots. It appears that the result is the integer part only.

The numbers I am trying to get is in the table

mmH2O ________Knots
15_____________ 30
26.5 ___________40
41.5 ___________50
60 _____________60
81.5 ___________70
106.5 __________80
134.5 __________90
166.5 _________100
201 ___________110
239.5 _________120


How do I calculate the correct value and still heed Steves advice to be careful of Math Overflow?


Thanks
aajgss

[Archangel]

Hello aajgss,
What level of resolution are wanting to display, I mean how many decimal places ?
You could multiply up by 10, 100, 1000 and display using DEC modifier and "." .
I didn't notice which PIC you are using but 18Fs can use long variables which if I am not mistaken are 32 bit vars.