Faulty results on arduino due

mjsneijders commented 2 years ago

Running the following code using your WMM_Tiny library on an Arduino Due results in an output of -4.80 degrees, while the calculator on https://www.ngdc.noaa.gov/geomag/calculators/magcalc.shtml#declination returns 2 degrees E.

do you have any idea where this almost 2.5 times difference comes from? it must have something to do with the negative latitude..... when i run using positive latitude and compare with the website calculator, the results look fine

code:

  uint8_t year = 22;
  uint8_t month = 3;
  uint8_t day = 4;

  double longitude = 52.964357;
  double latitude = -4.779369;  
  float Declination; 

  Serial.print("Longitude = "); Serial.println(longitude,6); 
  Serial.print("Latitude = ");  Serial.println(latitude,6); 
  Serial.println((String)"On date = "+ day + "-" + month + "-"  + year + "\n"); 

  wmm_init();  
  float wmmdate=wmm_get_date( year,  month,  day);
  E0000(latitude, longitude, wmmdate, &Declination); 

  Serial.println();
  Serial.println((String)"The calculated geomagnetic declination is: " + Declination + " degrees");

output:

Longitude = 52.964357
Latitude = -4.779369
On date = 4-3-22

The calculated geomagnetic declination is: -4.80 degrees

mjsneijders commented 2 years ago

never mind, i must have had my blond genes playing up... lat/lon reversed

miniwinwm commented 2 years ago

Thanks for the interest in the library anyway. I'll get on to fixing the typo.

On Sat, 5 Mar 2022 at 09:43, mjsneijders @.***> wrote:

never mind, i must have had my blond genes playing up... lat/lon reversed

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miniwinwm / WMM_Tiny

Faulty results on arduino due #4