MagneticModel are flipping Bx, By componets and inverting Bz

[Anonymous]

I noted that MagneticModel appears to be changing the magnetic field components:
Bx = By
By = Bx
Bz = -Bz
I edited example-MagneticModel.cpp to output the data as the program geomag70 in https://www.ngdc.noaa.gov/IAGA/vmod/geomag70_linux.tar.gz
then I get:

$ ./example-MagneticModel 
year:2012 D:0.184591 I:43.204 H:35137.3 Bx:113.202 By:35137.1 Bz:-33000.7 F:48204.5
$ geomag70 /usr/local/share/IGRF12.COF 2012,1,1 D M8820 27.99 86.93
...
   Date          D           I           H        X        Y        Z        F
   (yr)      (deg min)   (deg min)     (nT)     (nT)     (nT)     (nT)     (nT)
  2012.00     0d  11m    43d  12m   35137.2  35137.1    113.2  33001.0  48204.7
...

Components D, I, H and F are basicaly the same (converting min to degrees), but Bx = Y, By = X and Bz = -Z

Is this the expected result?

[Charles Karney]

The documentation for the MagneticModel class, operator(), says that

Bx = easterly component
By = northerly component
Bz = vertical (up) component

What are the conventions for X, Y, Z for geomag70?

[Anonymous]

My bad, I didn't pay enough atention to the documentation. Geomag70 follows the following convention:
X = northerly
Y = esterly
Z = vertical (down)
And I'm so used with that convention that I just forgot to check if the program was using another one.