• pressure normalization of BMP180

Hello all,
i like to have a normalization of the pressure value of the BMP180. Formula is:

pressure / pow(1.0 - altitude/44330.0, 5.255)

How do I do this with a rule and variable?? Especially with the complex formula?

Thanks

• It will be possible with the next release (which will be available shortly).

Here is a proof of concept:

"variables": [
{
"name": "pressure",
"value": 1024
},
{
"name": "altitude",
"value": 500
},
{
"name": "normalizedPressure",
"expression": "\$pressure/pow(1.0-\$altitude/44330.0,5.255)"
}
]

"It always takes longer than you expect, even when you take into account Hofstadter's Law.", Hofstadter's Law

• @temp released pimatic@0.9.35

"It always takes longer than you expect, even when you take into account Hofstadter's Law.", Hofstadter's Law

• I linke to use this Formula

'pressure*(1-((0.0065*altitude)/(21+0.0065*altitude+237.15)))**(-5.257)'

because it is more accurate but it always display expression error…
Why? Whats wrong?

• **

What is **? pow()?

"It always takes longer than you expect, even when you take into account Hofstadter's Law.", Hofstadter's Law

• **

What is **? pow()?

• @temp The following works for me, but I am not sure this what is intended:

\$pressure*pow((1-((0.0065*\$altitude)/(21+0.0065*\$altitude+237.15))),-5.257)

The result is 1093 dot something for the values I had in the previous example

"It always takes longer than you expect, even when you take into account Hofstadter's Law.", Hofstadter's Law

• 237.15

I think think this should be 273,15 for 0 deg C

EDIT: Just checked my result against the online calc which looks OK. Corrected expression:

\$pressure*pow((1-((0.0065*\$altitude)/(21+0.0065*\$altitude+273.15))),-5.257)

"It always takes longer than you expect, even when you take into account Hofstadter's Law.", Hofstadter's Law

• @mwittig thanks

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