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MS Excel Help - Saturation Points ?

  1. Nov 30, 2007 #1
    MS Excel Help -- Saturation Points ?!

    Does anyone know how to do this with if-then statements or something else?

    For example:

    I want to analyze inflow and outflow in a tank, when the volume reaches zero then it's empty of course--so I shouldn't have a negative volume after this, volume should just be zero until I can finally get a large enough inflow. Say I'm doing this in minutes.
     
  2. jcsd
  3. Nov 30, 2007 #2

    berkeman

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    Sounds like the floor function in Excel would do what you want. Try help floor.
     
  4. Nov 30, 2007 #3

    berkeman

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    Oops, no. Foor is different. Using an IF statement would probably be best.
     
  5. Nov 30, 2007 #4

    berkeman

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    So use =IF(cell_reference < 0, 0, cell_reference)

    Here are two columns of numbers: The first is just the numbers, and the second column uses the above equation in each cell, with the cell_reference equal to the cell to its left. Just use control-d to pull the first cell equation down to all the cells in the right column to get the calculations done.

    Code (Text):
    10  10
    9   9
    8   8
    7   7
    6   6
    5   5
    4   4
    3   3
    2   2
    1   1
    0   0
    -1  0
    -2  0
    -3  0
    -4  0
    -5  0
    -6  0
     
     
    Last edited: Nov 30, 2007
  6. Nov 30, 2007 #5

    FredGarvin

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    I'm not sure what your volume calcs look like, but a standard IF() function in Excel would look like:

    IF(A1>0,ENTER CALC HERE,0) where A1 is the cell that would display the tank volume.
     
  7. Dec 4, 2007 #6

    stewartcs

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    You have to use VBA in Excel to use the full IF-THEN-ELSE statement.

    IF dummy > 10 THEN
    msgbox "dummy is greater than 10"
    ELSE
    msgbox "dummy is less than or equal to 10"
    END IF


    I'm not sure what you are asking about the rest of the question.
     
  8. Dec 4, 2007 #7

    russ_watters

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    No, the excel command contains the "else". It's the 3rd term in Fred's statement.

    Also, my read of the question says that both the first and second terms should be the equation - first as an argument, then as an output. Ie:

    =if([your function]>0,[your function],0)

    But it is tough to know for sure without getting more specifics of the problem.
     
  9. Dec 4, 2007 #8

    stewartcs

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    Never said it wasn't.

    My comment was that if you want to use the full functionality to use VBA. That way you can use nested statements (a lot easier anyway), plus loops, etc... It just depends on how complicated your calculation is (or what ever you need the app to do).

    If you need just one simple If-Then-Else statement, then of course the Excel function IF() would work just fine.
     
  10. Dec 5, 2007 #9
    I guess berkeman's solution makes sense, I have to look at my excel model *later* and see if that would work. Thanks.
     
  11. Dec 5, 2007 #10
    Here's a stripped down version of the stuff I was working on.

    It's a model of the volume in a tank, ignoring how a real tank's outflow would change with the amount of mass in the tank.
     
    Last edited by a moderator: Dec 6, 2007
  12. Dec 16, 2007 #11

    CRGreathouse

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    Homework Helper

    In this particular case the IF statement is overkill. You could just use
    =MAX(0, [formula here])
     
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