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  1. GMAT
  2. GMT-3173

Clarification needed on HA output range

    Details

    • Type: Bug
    • Status: Closed (View Workflow)
    • Priority: P1
    • Resolution: Fixed
    • Affects Version/s: None
    • Fix Version/s: None
    • Labels:
      None
    • Environment:

      Windows 7 Enterprise 64-bit
      2012-10-15 build

      Description

      The attached script outputs Moon-centered HA for a LEO spacecraft. This is an angular parameter, so I would expect it to have a range of 0–360 or -180–180.

      But the range from GMAT is odd: it looks like -360–360. Can you check the code and see if it's being modded to any particular range?

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            Hide
            shughes Steven Hughes added a comment - - edited

            Hyperbolic anomaly is a weird parameter in that it is NOT an angle but a measure of area. So, HA does not have a range like other anomalies. From a mathematical perspective, sinh(X) = (e^x - e^(-x))/2 which is NOT a periodic function. Hence, you cannot use modular arithmetic on asinh. Another way of saying this is sinh(.1) ~= sinh(.1 + 2*pi).

            Show
            shughes Steven Hughes added a comment - - edited Hyperbolic anomaly is a weird parameter in that it is NOT an angle but a measure of area. So, HA does not have a range like other anomalies. From a mathematical perspective, sinh(X) = (e^x - e^(-x))/2 which is NOT a periodic function. Hence, you cannot use modular arithmetic on asinh . Another way of saying this is sinh(.1) ~= sinh(.1 + 2*pi).
            Hide
            jjkparker Joel Parker added a comment -

            Gotcha, I'll remove the periodic range from the spec.

            Show
            jjkparker Joel Parker added a comment - Gotcha, I'll remove the periodic range from the spec.

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                • Created:
                  Updated:
                  Resolved: