Formula: Errors

QFFE_209: "Illegal 'acos' argument : 'value'"

Arc cosine of the argument can not be calculated.

Cause

• Arc cosine argument is either less than -1 or greater than 1

  acos(log(3))

  Illegal 'acos' argument : '1.09861'

• Arc cosine argument becomes either less than -1 or greater than 1 due to rounding errors

  acos(1e300 / 1e150 ^ 2)

  Illegal 'acos' argument : '1'

Resolution

• Check that the value of arc cosine argument is between -1 and 1.
• If the cause is in rounding errors, try to change the order of operations to reduce their impact.