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 A_MINUS()
 Subtract all elements of an array by a value or an array of values
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 Syntax

    A_MINUS( <aTarget>,
             <nValue> | <aValue>,
             [<aSource>] )

 Arguments

    <aTarget> is the array to be modified.  If <aSource> is not
    specified then each element of <aTarget> will be subtracted by the
    <nValue> or element by element by <aValue>.

    <nValue> or <aValue> is either a value or an array of values to be
    subtracted.

    <aSource> is an optional array of values.  If specified, then each
    element of <aTarget> will be filled with the corresponding value
    in <aSource> subtracted by <aValue> or <nValue>.

 Returns

    Although there is no return value, the <aTarget> array is modified.

 Description

    A_MINUS() provides a means to perform a subtraction of every
    element in the <aSource> array if specified or the <aTarget> array
    if not.  Each element of the <aSource> or <aTarget> array has
    <nValue> or <aValue> subtracted from it.  The result of the
    subtraction replaces the value in the <aTarget> array.

    A_MINUS() can be performed on any integer or floating point type
    array. These include the (T)iny, (I)nteger, (L)ong, (F)loat and
    (D)ouble.  Mixing of these types is allowed.

 Notes

    If the <aTarget> and the <aSource> arrays are not the same
    dimensions, the results will be a subtraction element for element
    as the arrays are aligned in memory.  See chapter two for how
    arrays are aligned in memory.

 Examples

    // Declare three double type arrays for this function.
    LOCAL rows, cols

    rows = 10
    cols = 20
    aSource = A_DECLARE( "D", rows, cols )
    aTarget = A_DECLARE( "D", rows, cols )
    aSubMe  = A_DECLARE( "D", rows, cols )

    // Fill the target array with 10's
    A_FILL( aTarget, 10, A_(1, 1), rows * cols )

    // Subtract 2 from every element in the target array
    A_MINUS( aTarget, 2 )
    ? A_RETRIEVE( aTarget, A_( 4, 5 ) )    // Result: 8.0


    // Fill the source array with 10's
    A_FILL( aSource, 10, A_(1, 1), rows * cols )

    // Subtract five from every element in the source array and
    // put the result in the target array.
    A_MINUS( aTarget, 5, aSource )
    ? A_RETRIEVE( aTarget, A_( 4, 5 ) )    // Result: 5.0


    // Fill the "subtract me" array with 4's
    // Remember the source array still has all 10's
    A_FILL( aSubMe, 4, A_(1, 1), rows * cols )

    // Subtract from every element in the source array the
    // value in every matching element of the "subtract me"
    // array and put the result in the target array.
    A_MINUS( aTarget, aSubMe, aSource )
    ? A_RETRIEVE( aTarget, A_( 4, 5 ) )    // Result: 6.0