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ptc-49772311-Visitor
1-Visitor
February 21, 2013
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How do you solve for a variable?

  • February 21, 2013
  • 3 replies
  • 1732 views

I was just wondering how do you solve for a variable in MATHCAD. I have a function defined as

h(v,k,c):=(k/c)(v/c)^(k−1)exp(−(v/c)^(k))

This is a weibull distribution fucntion. k and c are already defined constants k = 1.5 and c = 15. I take the derivative

dh(v,k,c):=(d/dv)h(v,k,c)

I want to set it to zero and solve for v but when I set dh(v,k,c)=0 I get a 'variable is undefined error'. Anyone know how to set the equation equal to zero and solve for v?

    Best answer by ViktorKorobov

    In Mathcad 14:

    weibull.GIF

    Viktor

    3 replies

    ViktorKorobov1-VisitorAnswer
    1-Visitor
    February 21, 2013

    In Mathcad 14:

    weibull.GIF

    Viktor

      ptc-49772311-VisitorAuthor
      1-Visitor
      February 21, 2013

      Thanks. that was very helpful.

        Werner_E
        Werner_E25-Diamond I
        25-Diamond I
        February 21, 2013

        I want to set it to zero and solve for v but when I set dh(v,k,c)=0 I get a 'variable is undefined error'. Anyone know how to set the equation equal to zero and solve for v?

        You have to use the boolean equal sign (strg and +) and not the numeric evaluation equal sign.

        You could either use the symbolic solve (as Viktor showed) or a numeric solve block.

        Find both methods in attached file.

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