Name

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  MGH_TF_NEGATIVE

Purpose

---

  This function is designed for use with the TICKFORMAT and
  TICKFRMTDATA properties of IDLgrAxis. Given a real value, it
  returns a string representing the additive inverse.
  MGH_TF_NEGATIVE is a special case of MGH_TF_LINEAR.

Calling Sequence

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  Result = MGH_TF_NEGATIVE(Direction, Index, Value)

Positional Parameters

---

  Direction (input)
    Axis direction, required by the TICKFORMAT interface but ignored.
  Index (input)
    Axis index, required by the TICKFORMAT interface but ignored.
  Value (input)
    The real value to be formatted.

Keyword Parameters

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  DATA (input, structure)
    Specify this keyword to control the format. The keyword value
    should be a structure with the tag "format".The default is not
    to apply an explicit format.

Return Value

---

  The function returns a scalar string.
###########################################################################
  This software is provided subject to the following conditions:
  1. NIWA makes no representations or warranties regarding the
    accuracy of the software, the use to which the software may
    be put or the results to be obtained from the use of the
    software. Accordingly NIWA accepts no liability for any loss
    or damage (whether direct of indirect) incurred by any person
    through the use of or reliance on the software.
  2. NIWA is to be acknowledged as the original author of the
    software where the software is used or presented in any form.
###########################################################################

Modification History

---

  Mark Hadfield, 1999-05:
    Written.
  Mark Hadfield, 2002-12:
    Changed the default number-to-string conversion function from
    FORMAT_AXIS_VALUES to MGH_FORMAT_FLOAT--see comments in
    MGH_TF_LONGITUDE.