if condition

SupportCommunity FPScript if condition

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  • #12506

    I have serious problems to implement `if` conditions. For instance I have to calculate dewpoints which is not any obstacle, but afterwards I attempt to sum these dewpoints up to partial pressures and it doesn`t work. To illustrate my problem I give the program code:

    dim tau,pv,i,s,ppm

    For Each Row i In CH1 Do

    tau=ch1.Y/2*130-110 // dewpoint

    if tau<0 then
    pv=611.15*exp(22.542*tau/(tau+273.48)); // partial pressure
    else
    pv=611.21*exp(17.502*tau/(240.97+(tau*65-110)));
    end
    ppm=pv/101325*10^6

    end

    #8169

    I have serious problems to implement `if` conditions. For instance I have to calculate dewpoints which is not any obstacle, but afterwards I attempt to sum these dewpoints up to partial pressures and it doesn`t work. To illustrate my problem I give the program code:

    dim tau,pv,i,s,ppm

    For Each Row i In CH1 Do

    tau=ch1.Y/2*130-110 // dewpoint

    if tau<0 then
    pv=611.15*exp(22.542*tau/(tau+273.48)); // partial pressure
    else
    pv=611.21*exp(17.502*tau/(240.97+(tau*65-110)));
    end
    ppm=pv/101325*10^6

    end

    #8806
    Bernhard KantzBernhard Kantz
    Moderator

    You have forgotten to return the result:

    
    For
    ...
    End
    ppm //or return ppm
    

    But in this case the result is only the ppm of the last value. If you want to calculate the ppm of each value try this

    
    Dim tau = ch1.Y/2*130-110 // dewpoint
    Dim idxAbove = ValuesAboveLevel(tau, 0, EVENT_INDEX)
    tau = 611.15*exp(22.542*tau/(tau+273.48)) // partial pressure
    tau[idxAbove] = 611.21*exp(17.502*tau[idxAbove]/(240.97+(tau[idxAbove]*65-110)))
    tau/101325*10^6
    

    FPScript is a vectorial script language. Therefore you need no loop to manipulate the whole signal.

    support@weisang.com

    #8807

    Thank you for your support. The formula is working rather well, but if the signal is rising up to 1.7 the results become too high.
    Signal:
    21 1,68925
    22 1,71725
    23 1,7133125
    24 1,735625
    25 1,732875
    26 1,736
    27 1,7446875
    28 1,7549375
    29 1,758875
    30 1,7646875
    31 1,7715625
    32 1,7709375
    33 1,769125
    34 1,77425
    35 1,770125
    36 1,76425
    37 1,7693125
    38 1,77175
    39 1,7569375
    40 1,762
    41 1,7371875
    42 1,7355
    43 1,7155625
    44 1,692125
    Results:
    21 5933,50484
    22 2696401011
    23 2514035768
    24 3697558728
    25 3530971112
    26 3720759050
    27 4291879038
    28 5053249400
    29 5372463216
    30 5872151797
    31 6508674208
    32 6448717840
    33 6277230852
    34 6771345639
    35 6371406764
    36 5833334034
    37 6294807061
    38 6526743852
    39 5213478477
    40 5636824868
    41 3795002615
    42 3689851293
    43 2616946068
    44 6025,680376

    I really do not know what the formula sums up.
    Code:
    Dim tau = ch1.Y/2*130-110 // dewpoint
    Dim idxAbove = ValuesAboveLevel(tau, 0, EVENT_INDEX)
    tau = 611.15*exp(22.542*tau/(tau+273.48)) // partial pressure
    tau[idxAbove] = 611.21*exp(17.502*tau[idxAbove]/(240.97+(tau[idxAbove])))
    tau/101325*10^6

    #8808
    Bernhard KantzBernhard Kantz
    Moderator

    Use

    
    tau[idxAbove] = 611.21*exp(17.502*tau[idxAbove]/(240.97+(tau[idxAbove]*65-110)))
    

    instead of

    
    tau[idxAbove] = 611.21*exp(17.502*tau[idxAbove]/(240.97+(tau[idxAbove])))
    

    support@weisang.com

    #8809

    The problem, however, is that I modified my formula. That is why I need the new one:
    tau[idxAbove] = 611.21*exp(17.502*tau[idxAbove]/(240.97+(tau[idxAbove])))
    I sumed it up by my calculator and there was not such high figure as result.

    #8810
    Bernhard KantzBernhard Kantz
    Moderator

    The code “tau = …” changes all tau values. Therefore the next line uses the wrong values to calculate the values above 0.

    Use the IndexNot function to calculate the indices of tau values below 0.

    
    Dim tau = ch1.Y/2*130-110   
    Dim idxAbove = ValuesAboveLevel(tau, 0, EVENT_INDEX)
    Dim idxBelow = IndexNot(idxAbove, NumberOfRows(ch1))
    tau[idxBelow] = 611.15*exp(22.542*tau[idxBelow]/(tau+273.48))               
    tau[idxAbove] = 611.21*exp(17.502*tau[idxAbove]/(240.97+(tau[idxAbove])))
    tau/101325*10^6
    

    support@weisang.com

    #8811

    Hello,
    first of all I would like to thank you. Now I have a last request: I would like to search the maximum of the signal and let the program sum it up from this maximum.
    dim tau = ch1.y/2*130-110
    Dim idxAbove = ValuesAboveLevel(tau, 0, EVENT_INDEX)
    Dim idxBelow = IndexNot(idxAbove, NumberOfRows(ch1))
    tau[idxBelow] = 611.15*exp(22.542*tau[idxBelow]/(tau[idxBelow]+273.48))
    tau[idxAbove] = 611.21*exp(17.502*tau[idxAbove]/(240.97+tau[idxAbove]))
    tau/101325*10^6

    #8812
    Bernhard KantzBernhard Kantz
    Moderator

    You can use the Maximum-function to calculate the maximum of the signal. You find all FPScript functions in the function wizard.

    See also the FlexPro Online Help.

    Support@weisang.com

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