Command: ChnApprYCalc

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Command: ChnApprYCalc

Approximates a signal.

Input Parameters

XW	Specifies the data channel that contains the x-values of the signal. If the associated y-channel is a waveform channel, you do not need to specify this channel.
Y	Specifies the data channel that contains the y-values of the signal.
SamplingPointChn	Specifies the data channel containing the interpolation points. Channel variable
ResultChannel	Specifies the result channel containing the y-values of the approximation function.

Return Parameters

Note  If you want to use waveform channels in this command, follow Rule 2.2 for Calculating with Waveform Channels.

Global Parameters 

ApprAnsatzFct(i)

Specifies the function terms for the setup function. Enumeration variable i = 1 ... 26 Enumeration variable with the following selection terms Script Term Interface Term, Explanation "-" - "Yes" Yes Valid Settings ApprAnsatzFct (1) Constant ApprAnsatzFct (2) x ApprAnsatzFct (3) x^2 ApprAnsatzFct (4) x^3 ApprAnsatzFct (5) x^4 ApprAnsatzFct (6) x^5 ApprAnsatzFct (7) x^6 ApprAnsatzFct (8) x^7 ApprAnsatzFct (9) x^8 ApprAnsatzFct (10) x^9 ApprAnsatzFct (11) x^10 ApprAnsatzFct (12) x^11 ApprAnsatzFct (13) 1.x ApprAnsatzFct (14) 1/x^2 ApprAnsatzFct (15) 1/x^3 ApprAnsatzFct (16) 1/x^4 ApprAnsatzFct (17) ln(x) ApprAnsatzFct (18) log(x) ApprAnsatzFct (19) e^x ApprAnsatzFct (20) 10^x ApprAnsatzFct (21) sqrt(x) ApprAnsatzFct (22) e^(x^2) ApprAnsatzFct (23) x^(1/3) ApprAnsatzFct (24) 10^(x^2) ApprAnsatzFct (25) e^(-x) ApprAnsatzFct (26) e^(-x^2)   Note  You can select a maximum of ten setup functions simultaneously.

Return Parameters 

ApprAnsatzCoef(i)	Receives the coefficients of the setup function. Floating-point number variable i = 1 ... 10
ApprPrecision	Receives the coefficient of determination of an approximation. Floating-point number variable Access: Read only

Note  The values in the x-channel must be monotone increasing.

DIAdem approximates the signal with a function that contains a linear combination of individual and independent setup functions. DIAdem first calculates the coefficients of the function. DIAdem then evaluates the calculated approximation function in the x-range specified by the XChnNo interpolation points channel.

DIAdem uses the Gauss method of least squares for approximation.

Note  If the selected setup function results in a curve that deviates substantially from the exact solution, DIAdem displays an error message.

Note  The ApprAnsatzOff command clears the checkboxes for the selected setup function terms.

Refer to the Help page Approximation for further information.

Examples

The following example calculates an approximation with the a1+a2*x+a3*x^2 setup function. DIAdem saves the results of the evaluation of the approximation function for the specified interpolation points channel in the Results channel group. The input channels are accessed through channel objects.

Dim oMyGroup, oMyXChannel, oMyYChannel, oMyY1Channel, oMyResultChn
Call ApprAnsatzOff                   ' Deactivates all function terms
ApprAnsatzFct(1) = "Yes"             ' Activates function term constant
ApprAnsatzFct(2) = "Yes"             ' Activates function term x
ApprAnsatzFct(3) = "Yes"             ' Activates function term x^2
Set oMyXChannel = Data.Root.ChannelGroups(1).Channels(1)
Set oMyYChannel = Data.Root.ChannelGroups(1).Channels(2)
Set oMyY1Channel = Data.Root.ChannelGroups(1).Channels(3)
Set oMyResultChn = ChnApprYCalc(oMyXChannel, oMyYChannel, oMyY1Channel, "Results/ApproximatedY")
Call MsgBox("Result channel: " & oMyResultChn(1).ChannelGroup.Name & "/" & oMyResultChn(1).Name)

dd.ApprAnsatzOff # Deactivates all function terms
dd.ApprAnsatzFct[1] = "Yes" # Activates function term constant
dd.ApprAnsatzFct[2] = "Yes" # Activates function term x
dd.ApprAnsatzFct[3] = "Yes" # Activates function term x^2
oMyXChannel = dd.Data.Root.ChannelGroups(1).Channels(1) 
oMyYChannel = dd.Data.Root.ChannelGroups(1).Channels(2) 
oMyY1Channel = dd.Data.Root.ChannelGroups(1).Channels(3) 
oMyResultChn = dd.ChnApprYCalc(oMyXChannel, oMyYChannel, oMyY1Channel, "Results/ApproximatedY") 
print("Result channel: " + oMyResultChn(1).ChannelGroup.Name + "/" + oMyResultChn(1).Name) 

The following example calculates an approximation with the a1+a2*x+a3*x^2 setup function. DIAdem saves the results of the evaluation of the approximation function for the specified interpolation points channel in the Results channel group. The input channels are accessed through the channel reference.

Dim oMyResultChn
Call ApprAnsatzOff                   ' Deactivates all function terms
ApprAnsatzFct(1) = "Yes"             ' Activates function term constant
ApprAnsatzFct(2) = "Yes"             ' Activates function term x
ApprAnsatzFct(3) = "Yes"             ' Activates function term x^2
Set oMyResultChn = ChnApprYCalc("[1]/[1]","[1]/[2]","[1]/[3]","Results/ApproximatedY")
Call MsgBox("Result channel: " & oMyResultChn(1).ChannelGroup.Name & "/" & oMyResultChn(1).Name)

dd.ApprAnsatzOff # Deactivates all function terms
dd.ApprAnsatzFct[1] = "Yes" # Activates function term constant
dd.ApprAnsatzFct[2] = "Yes" # Activates function term x
dd.ApprAnsatzFct[3] = "Yes" # Activates function term x^2
oMyResultChn = dd.ChnApprYCalc("[1]/[1]","[1]/[2]","[1]/[3]","Results/ApproximatedY") 
print("Result channel: " + oMyResultChn(1).ChannelGroup.Name + "/" + oMyResultChn(1).Name) 

Dialog Box Call

Call SUDDlgShow("Main", ResourceDrv & "AnaChnApprCalc")

Approximate

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