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gwestbrook1-Visitor
1-Visitor
June 25, 2015
Solved

Why does this vector not compute?

  • June 25, 2015
  • 2 replies
  • 2237 views

Starting to feel a bit moronic here.

I've included a short worksheet illustrating my problem.  I'm trying to graduate from simple calculation to using vectors.  As you will see, I have an equation for M for which I can calculate a value easily enough.  Units work out OK too.

When I attempt to make a vector (in my world, this lambda equates to a wavelength but that's irrelevant to the problem), I get an error complaining of the units.

Not really sure if that's really the issue here; can anybody else shed some light?

Best answer by LucMeekes

You've put a multiplication between M and (lambda, 300*K), dissecting the function name from its argument list. Remove that and it should work fine.

Well not completely,  the funny error message is gone, but you get a single result for an input vector.

In order to get a vector of results, you need to vectorize the definition (the right-hand-side of the definition of the function M.

To do that, select it and press [CTRL -], it will show an arrow above. And the result of the last evaluation will be a vector.

Succes!
Luc

2 replies

L
LucMeekes23-Emerald IVAnswer
23-Emerald IV
June 25, 2015

You've put a multiplication between M and (lambda, 300*K), dissecting the function name from its argument list. Remove that and it should work fine.

Well not completely,  the funny error message is gone, but you get a single result for an input vector.

In order to get a vector of results, you need to vectorize the definition (the right-hand-side of the definition of the function M.

To do that, select it and press [CTRL -], it will show an arrow above. And the result of the last evaluation will be a vector.

Succes!
Luc

    S
    StuartBruff23-Emerald V
    23-Emerald V
    June 25, 2015

    In addition to the extra character between the M and the opening parenthesis,  you will need to use the vectorize operator (ctl-minus) to get a result for each lambda.  Otherwise Mathcad will interpret the  lambda multiplication in the  (power to the fifth and the exponential) as a vector dot product.

    Stuart

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      gwestbrook1-VisitorAuthor
      1-Visitor
      June 26, 2015

      Thanks!

      Based on the recommendation of someone on this forum, I've ordered "Essential MathCAD for Engineering, Science, and Math".  That should help me get better at this.

      M
      MikeArmstrong1-Visitor
      1-Visitor
      June 26, 2015

      I would highly recommend using this forum and the material passed by the members. Good luck.

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