Hi, I am using this map function. VAL= map(a1,0,90,80,30) . When a1 =0, val=80. when a1 =90 val=30. I am getting when a1=37.69, VAL=60. The map function only works in integers so a1 would be seen as 38.
Can anybody give me the maths here to calculate VAL from the value of a1? I cannot see how it is calculated.
Thanks.
Use this variation which can handle float
float mapfloat(float x, float in_min, float in_max, float out_min, float out_max)
{
return (x - in_min) * (out_max - out_min) / (in_max - in_min) + out_min;
}
a1 would be "seen" as 37. Going from float to integer truncates.
a7
you should read the Arduino reference, it is explained in
https://docs.arduino.cc/language-reference/en/functions/math/map/
I'd suggest you dont use the map function. Where did you hget those values?
using my figures and the maths I am getting the 60 return. thanks for the extra accuracy although for my purposes integers are accurate enough. It is no wonder I could not figure out the maths for getting 60. 37 is slightly more accurate than 38 as suggested by alto777.