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PH_97403251-Visitor
1-Visitor
December 3, 2020
Solved

Please Help me with this bug - Integral functions and plotting

  • December 3, 2020
  • 1 reply
  • 5401 views

Hi all, I am new to MathCAD and i can just not figure out this bug. 

I am trying to plot a chart for beam deflection on prime4. I am using an old mathcad15 sheet as a reference and the cad 15 sheet calculates it fin so this should work but I cannot figure out why it's giving me an error. 

 

PH_9740325_0-1607014677259.png

PH_9740325_1-1607014724267.png

 

 

    Best answer by Fred_Kohlhepp

    I need to point out that both of you have run afoul of the "English Units" tribulation.

     

    "lb" is a unit of mass.  We're dealing with forces (lbf)

     

    Attached is Werner's sheet modified (sorry Werner) to correct unit issues (including degrees.)

     

    I only have Express, if opened in full Mathcad it should calculate properly.

    1 reply

    W
    Werner_E25-Diamond I
    25-Diamond I
    December 4, 2020

    Even though Prime would accept its its bad math to use the same variable as limit and variable of integration like in

    Werner_E_1-1607042984565.png

    But as Prime is unit aware, you must even add the unit to a value of zero. This is different to real Mathcad which uses static unit checking. So a correct approach would be something like

    Werner_E_2-1607043053204.png

    Doing this consequently gives you

    Werner_E_3-1607043416113.png

    BTW, you should Prime let do the conversion from radian to degree and vice versa for you. There is a predefined constant/unit factor "deg" which is pi/180.

     

     

     

      P
      PH_97403251-VisitorAuthor
      1-Visitor
      December 4, 2020

      Thank you so much!! i will give this a go and report back! it looks like this will work!

      W
      Werner_E25-Diamond I
      25-Diamond I
      December 4, 2020

      The only thing really necessary is to add a unit of length to the lower integral limit.

      I also deleted the constant functions E and I because I see no reason for defining them. If you need them later you might re-add them, of course.

       

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