Hyperbolic Trig functions

[Ken01]

Owing to VB6 not having the standard Hyperbolic Trig functions (Sinh, Cosh etc) I have written routines to calculate them from scratch,
e.g Sinh(x) = (e^x - e^-x)/2 and Cosh(x) = (e^x + e^-x)/2
However when multiple calculations are required within a loop then the process grinds to a halt as it is a memory hog
(I am trying to calculate X, Y co-ordinates for a parametric graph).

Have any of your experts any ideas for a resolution ?

 

[mmerlinn]

How are we supposed to pinpoint a solution for you when you do not show us what you are doing?

 

[strongm]

Hmm - I just wrote a loop that calculates HSin and and HCos 100000 times, and it was practically instantaneous.. Perhaps we need to see your code

 

[Ken01]

Here is the sample code (calls to the relevant trig functions are highlighted :
It was adapted from code downloaded from a VB 6 "shareware" website

Variable declarations
Rem Main Loop
For Count = Xst - 2 * MyPi To Xst + 2 * MyPi Step 3
'Step++ = Faster; Step-- = Slower
'
If Option1 = True Or Option3 = True Then
y = -Sin((Count - Xst) / One) * One + Yst
y1 = -Atn((Count - Xst) / One) * One + Yst
Else
y = Atn(Sin(Count + Xst) / One) * One + Yst
y1 = (MSinh((Count + Xst)) / One) * One + Yst ********************************
End If
y2 = -((Count - Xst) / One) ^ 3 * One + Yst
If Option1 = True Or Option2 = True Then
If Count > Xst Then y3 = -Log(Atn(Count - Xst) / One) * One + Yst
Else
If Count > Xst Then y3 = -Log(Tan(Count - Xst) / One) * One + Yst
End If

If Option3 = False Then
y4 = -Cos((Count - Xst) / One) * One + Yst
Else
y4 = (MCosh((Count - Xst)) / One) * One + Yst *********************************
End If

'Draw ...
Picture1.PSet (Count, y), vbBlue ' &HFFFF&
Picture1.PSet (Count, y1), vbGreen ' &H8000&
Picture1.PSet (Count, y2), vbMagenta ' &HC0&
If Count > Xst Then Picture1.PSet (Count, y3), &HFF0000
Picture1.PSet (Count, y4), vbRed ' &HFF&
DoEvents 'Without this line drawing is not interesting!
Next Count

=============================================================================================================

Public Function MSinh(Ival)
Ival = Ival / 16
MSinh = ((2.718 ^ Ival) + (2.718 ^ (Ival * -1)) / 2)
Print #1, "MSinh : " & MSinh & " : " & Ival

End Function


Public Function MCosh(Ival)
Ival = Ival / 16
MCosh = (2.718 ^ Ival) - (2.718 ^ (Ival * -1))
Print #1, "Mcosh : " & MCosh & " : " & Ival

End Function

Public Function Mtanh(Ival)
On Error Resume Next
Dim jx1 As Double, kx1 As Double
jx1 = MCosh(Ival): kx1 = MSinh(Ival)
Mtanh = jx1 / kx1
Ival = Ival / 16

Print #1, "Mtanh : " & Mtanh & " : " & Ival

End Function

 

[strongm]

I'd suggest that

Print #1, "MSinh : " & MSinh & " : " & Iva
Print #1, "Mcosh : " & MCosh & " : " & Ival
Print #1, "Mtanh : " & Mtanh & " : " & Ival

are what are slowing things down

 

[strongm]

(and do events won't be helping ...)