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  1. Moodle
  2. MDL-65182

Gradebook incorrectly calculates letter grade

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    Details

    • Type: Bug
    • Status: Development in progress
    • Priority: Major
    • Resolution: Unresolved
    • Affects Version/s: 3.4.8
    • Fix Version/s: None
    • Component/s: Gradebook
    • Labels:

      Description

      There is a bug where a letter grade is not calculated correctly due to floating point division. (floating point division by reciprocal multiplication).

      Reproduction Steps:

      1. Create a course with a total of 331 points.
      2. Assign a student points totaling 297.9.
      3. Make sure the grade scales is set to A- for a 90% or above.
      4. The 'real' grade value shows 90%, however the letter grade is B+.
      5. It appears PHP is calculating this similar to Pyhon.
        >>> 297.9/331
        0.8999999999999999
      6. This should be .90. 
        1. 297.9 / 331 equals exactly 90%.

      There are a number of tracker issues open related to rounding decisions. However ,this case seems to be a legitimate bug related to floating point division rather than a choice of rounding vs. truncating calculated values.

       

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