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MapleEvalhf - evaluate an object using hardware floats in external code
EvalhfMapleProc - evaluate a procedure using hardware floats in external code
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Calling Sequence
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MapleEvalhf(kv, s)
EvalhfMapleProc(kv, fn, n, args)
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Parameters
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kv
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kernel handle returned by StartMaple
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s
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Maple object object
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fn
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Maple FUNCTION object
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n
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number of arguments
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args
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array of n hardware floats
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Description
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These functions are part of the OpenMaple interface to Microsoft Visual Basic.
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The MapleEvalhf function evaluates an expression to a numerical value using the hardware floating-point of the underlying system. This command is equivalent to the Maple function, evalhf.
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The EvalhfMapleProc function evaluates the function, f(args), to a numerical value using evalhf. The n arguments provided are all 64-bit hardware floating-point numbers. The first argument must be inserted at args[1]. For example, to call f(3.14,2.718), set args[1] = 3.14, and args[2] = 2.718. The value at args[0] is not used.
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Examples
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Function MyNewton(ByVal kv As Long) As Double
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Dim i As Long
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Dim guess(2) As Double
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Dim tolerance As Double
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Dim f, fprime, x, initguess As Long
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' define a function in x to solve, and find it's derivative
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f = EvalMapleStatement(kv, "(x) -> x^3+2*x^2-9*x+2;")
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MapleAssign kv, ToMapleName(kv, "f", True), f
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fprime = EvalMapleStatement(kv, "unapply(diff(f(x),x),x);")
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x = ToMapleName(kv, "x", True)
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guess(1) = 1.1
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tolerance = 0.0001
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' find a root (abort after 500 iterations)
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For i = 0 To 500
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'test current guess
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If Abs(EvalhfMapleProc(kv, f, 1, guess(0))) <= tolerance Then
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i = 501 'break
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Else
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'refine guess
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guess(1) = guess(1) - EvalhfMapleProc(kv, f, 1, guess(0)) / _
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EvalhfMapleProc(kv, fprime, 1, guess(0))
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End If
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Next i
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If i = 500 Then
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MyNewton = -999999 'couldn't find root
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Else
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MyNewton = guess(1)
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End If
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End Function
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