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Thread: Wrong schedule formula calculation

  1. #1
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    Wrong schedule formula calculation

    Hello

    I'm trying to calculate something with a Revit schedule, but the calculated value i wrong?

    I've made to parameters called "GWP (MIP_K)" and "R_MIP - GWP".

    GWP (MIP_K) = 4,88
    R_MIP - GWP = 9,38

    And then I made the formula: GWP (MIP_K) / R_MIP - GWP

    But it's wrongly calculated to 1,47 and not 0,52 as it should be.



    If I use a "+" and not "/", its works perfectly fine, but I need to divide it.

    this formula: GWP (MIP_K) + R_MIP - GWP = *14,26‬ is correct??


    Can anybody tell me what migth be wrong?

  2. #2
    Moderator snowyweston's Avatar
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    Quote Originally Posted by Krogstrup View Post
    Can anybody tell me what migth be wrong?
    Wild guess, you've other parameters MIP_K and GWP elsewhere - and Revit is confusing them in your calculation because you have mathematical annotation in your parameter names, specifically:


    GWP (MIP_K)
    R_MIP - GWP

    you really don't want that stuff anywhere near numeric parameter names if you're ever going to do anything with formulas with their values.

  3. #3
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    I'd tried to change all the names from "-" to "_" and removed all parenthesis, but nothing has changed in the calculated value.

  4. #4
    Moderator snowyweston's Avatar
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    What are unit types of each parameter, and the unit type of the calculated value?

    (Screenshots help things immeasurably)

  5. #5
    Moderator DaveP's Avatar
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    I agree with Snowy. Not a good idea to use special characters in your parameter names.
    Even if it doesn't stuff up the calculation, it makes them hard to read & somewhat ambiguous.
    I'm not a big fan of spaces, either. BetterToUseCamelCase.
    If you absolutely MUST have () or - or * in your parameters, you'll have to surround the parameter with square brackets:
    [GWP (MIP_K)] / [R_MIP - GWP]
    And now that I look at that again, I thought your original formula divided GWP (MIP_K) by R_MIP and then subtracted GWP

  6. #6
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    I think I found the reason to my problem, but I can't seem to solve it.
    The schedule was unsorted and the numbers show where the total. I thought that this was fine, but it do not calculate the total values.

    Altso I changed a lot of the names and added the parameters to the formula. So now it's the "MIP_B"-group divided with "R_MIP"-group, which should equals X_GWP

    Schedule:
    Click image for larger version. 

Name:	total.PNG 
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ID:	36634

    Formula:
    Click image for larger version. 

Name:	Formula.PNG 
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ID:	36635


    When I sort the schedule I can see there the calculation error is. It calculates each category and do not use the totals. Is there any way to solve this problem?

    Sorted schedule:
    Click image for larger version. 

Name:	Sorting.PNG 
Views:	10 
Size:	7.8 KB 
ID:	36636

  7. #7
    Moderator snowyweston's Avatar
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    As you have discovered - calculated fields (in Revit schedules) do not, without some considerable hackery, do not consider in-line/row/column totals.

    Search out Ekkonap's posts on the method (I think in the "formulas for everyday use" thread)

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