Hello everyone, I have a question about programming in arduino. I don't know how to use ln(x) in arduino , I need the next function will be working.Help me please
Temperatura = 1 / 4.726504594 * pow(10, -3) - 4.012576310 * pow(10, -4) * ln(Resistencia) + 30.04841481 * pow(10, -7) * ln(pow(Resistencia, 3));
The function calls are log() (base e) and log10() (base 10). You might need to
#include <math.h>
Please use code tags when posting code.
4.726504594*pow(10,-3)*
See how the asterisks got eaten unless you use code tags?
So I was going to write that you can use
4.726504594e-3
as a constant. That’s 0.004726… google
arduino scientific notation
Know also that Arduino floating point is limited to 6-7 digits, even if you try using double.
a7
You need to look carefully at your equations and the limitations of the maths .
You have some very long numbers there, which are maybe quite meaningless in terms of their effect on any output .
Do some sensitivity checks - reduce the number of places in the numbers , remove some parts of the equation and see the effect in the output over a range of temperatures .
There maybe a better way to get your readings - simple curve fit over a limited range , look up table etc .
Look at the tolerances of the sensor too - that might not be as good as the maths
Depending on what you are doing there maybe a better easier sensor/transducer to use .
Temperatura = 1 / 4.726504594e-3
- 4.012576310e-4 * log(Resistencia)
+ 30.04841481e-7 * log(pow(Resistencia,3));
can be simplified as
+30.04841e-7 * 3 * log(Resistencia)
(ln 
log, supress redundant decimals)
Or, if you prefer
90.14524e-7 * log(Resistencia)
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