Doing Simple Math - getting the wrong answer

[Ingvar]

Hi Tom,

PBP can't handle fractions very well, the "**" and "*/" operators however makes it possible. 9/5 is 1.8 which PBP will trunctate to 1, not very useful. The "**" operator can handle the fractional part, this operaton makes an "invisible" division by 65536. 0.8*65536=52428.8 which we round up to 52429. Since your Dec_temp variable contains the temerature in tenths of a degree your formula needs to be ......

Dec_tempf=Dec_temp*(9/5) + 320 'Farenheit * 10

We rewrite this to ...
Dec_tempf=Dec_temp*1.8 + 320 'Farenheit * 10

Which is the same as .....
Dec_tempf=Dec_temp*1+Dec_temp*0.8 + 320 'Farenheit * 10

Using "**", we end up with ......
Dec_tempf=Dec_temp + Dec_temp**52429 + 320

Another thing, you can replace ......

' read data for temperature Temp
SSD4= (ssmax[24]>>4)
SSD3= (ssmax[24] & $f)
SSD2= (ssmax[23]>>4)
SSD1= (ssmax[23] & $f)

' convert to Decimal:

Dec_temp=(ssd4*4096)+(ssd3*256)+(ssd2*16)+ssd1

...... with ......

Dec_temp.highbyte = ssmax[24]
Dec_temp.lowbyte = ssmax[23]

/Ingvar

[Luciano]

Fahrenheit = Celsius * (212 - 32)/100 + 32


Example 30 Celsius to Fahrenheit:


30 * 180 / 100 + 32 = 86 Fahrenheit


Best regards,

Luciano