rscalc error

[s0161038]

Dear all,

I just reflashed my SD card after becoming read-only (LM4). After the recovery, I updated to firmware 20200720.

After restoring my backup I noticed the common rscalc function I use to check if the sun is up is not working any more on my system. 

Code:

function sun_is_up()

  -- returns number of minutes from 0:00 until sunrise and sunset
  latitude = 57
  longitude = 24.15
  log('gerund')
  sunrise, sunset = rscalc(latitude, longitude)

    date = os.date('*t')
    now = date.hour * 60 + date.min

    -- from 0:00 to sunrise
        if now < sunrise then
          alert('before sunrise')
    return false
    -- from sunset to 23:59
        elseif now > sunset then
          alert('after sunset')
    return false
        else
          alert('day')
    return true
        end
end

I always get the following error:


Common functions:7: attempt to call global 'rscalc' (a nil value)
stack traceback:

Does anybody have an idea what this is causing? 
Or does anybody know where the sourcecode of rscalc can be found to check what is going wrong?

thanks