Math problem

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- 16th February 2008, 09:01
Kamikaze47

Math problem

I have these 3 variables:

Code:

a VAR WORD b VAR WORD

a and b can be anywhere from 0 to 999.

I need to work out a way of displaying an a/b percentage on my LCD to 1 decimal place.

I thought of this;

Code:

a VAR WORD b VAR WORD pct VAR WORD pct=(a*1000)/b

which would give me the percent, with the last decimal being the decimal place. But this wont work if a=999 becuase 999*1000 is lager than a WORD can be.

I'm using PBP 2.46 so I cant use LONGs.

Any ideas? I'm sure this is possible, but i'm having a brain freeze.
- 16th February 2008, 09:14
skimask

DIV32...it's in the book.
- 16th February 2008, 09:29
Kamikaze47

thanks shimask

ive done this:

Code:

a VAR WORD b VAR WORD pct VAR WORD temp VAR WORD temp=a*1000 pct=DIV32 b

The only problem im having now is with rounding. If the real percentage is 65.28% id like it to display 65.3%, but of course im getting 65.2 because its just truncating the result.
- 16th February 2008, 09:37
skimask

Quote:

Originally Posted by Kamikaze47

thanks shimask

???????

Quote:

The only problem im having now is with rounding. If the real percentage is 65.28% id like it to display 65.3%, but of course im getting 65.2 because its just truncating the result.

Add .05 to everything...but that's a good trick since PBP doesn't support decimal points.
So how are you handling that?
- 16th February 2008, 10:26
sayzer

Think like GrandPA

If I get it right;

Why not this way?

Code:

 A VAR WORD B VAR WORD Solid VAR WORD Liquid VAR BYTE DoMath: '....get values from somewhere.. Solid = A/B Liquid = A//B IF Liquid DIG 0 >= 5 THEN Liquid = Liquid + 10 Liquid = Liquid DIG 1 LCDOUT $fe,1, "A:",DEC A, " B:",DEC B LCDOUT $fe,$c0,"%",DEC Solid,".",DEC Liquid PAUSE 30 GOTO DoMath

Something like this way???
- 16th February 2008, 10:53
Acetronics2

Hi, Sayzer

You' re to it ...

With showing the Half, now ( was DS 1820 Degrees with 3 Digits Leds...)

Code:

IF ( TEMP > 2631 and Temp < 3731) THEN ' -10 to 100°C Virgule = 1 ' round to 1/2 degré et show the 5/10 IF(Tempa // 10) < 3 THEN Tempa = ( Tempa/10)* 10 : GOTO AFF IF(Tempa // 10) < 8 THEN Tempa = (Tempa/10)*10 + 5 : GOTO AFF IF(Tempa // 10) > 7 THEN Tempa = (Tempa/10)*10 + 10 : GOTO AFF ENDIF Virgule = 0 IF (Tempa // 10) > 4 THEN Tempa = Tempa + 10 Tempa = Tempa/10 ' Show Degrees without tenths

Have a nice day

Alain