SysML 2.1b1 RTF Avatar
  1. OMG Issue

SYSML21 — Degree to Radian conversion imprecise

  • Key: SYSML21-320
  • Status: open  
  • Source: Ansys Government Initiatives ( Mr. Richard Page)
  • Summary:

    The definition of 'pi' provided in TrigFunctions::pi (KerML) also includes an invariant that specifies PI to 20 significant digits.

    However, in SI.sysml where we define 'degree', the conversion factor is listed as:

    attribute <'°'> degree : AngularMeasureUnit { :>> unitConversion: ConversionByConvention { :>> referenceUnit = rad; :>> conversionFactor = 1.745329E-02; :>> isExact = false; } } // conversionFactor should become pi/180
    

    It appears that this was intended to be a "TODO" that was never addressed!

    Having the conversion factor from degrees to radians only listed to "single precision" will be a severe problem for many engineering applications. We should instead depend on the actual "pi/180" expression as stated in the trailing comment

  • Reported: SysML 2.0b2 — Thu, 17 Jul 2025 21:33 GMT
  • Updated: Thu, 17 Jul 2025 21:57 GMT