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AlfredFlaßhaar15-Moonstone
15-Moonstone
December 27, 2022
Solved

Sici spiral, create graphic

  • December 27, 2022
  • 1 reply
  • 3809 views

Between Christmas and New Year's I want to "play" with curves on graphs in Mathcad 14. I am particularly interested in the graphical representation of the Sici spiral (or named after Nielsen). It is represented parameterized in the Cartesian x-y coordinate system by x=Si(t) and y=Ci(t) with t>0. The Si and Ci functions are found in Mathcad on the f(x) menu. But they don't work in the diagram, even though I followed the instructions from the "Help". That's why I didn't attach a test file here. What am I doing wrong?

Kind regards, Alfred Flasshaar

Best answer by Werner_E

Of course you can redefine the function and evaluate the necessary integrals numerically that way:

Werner_E_3-1672161514856.png

 

1 reply

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Werner_E25-Diamond I
25-Diamond I
December 27, 2022

As the help states, Si() and Ci() are symbolic only functions. They cannot be evaluated numerically and plotting requires numeric evaluation.

Werner_E_0-1672161020791.png

 

W
Werner_E25-Diamond IAnswer
25-Diamond I
December 27, 2022

Of course you can redefine the function and evaluate the necessary integrals numerically that way:

Werner_E_3-1672161514856.png

 

    W
    Werner_E25-Diamond I
    25-Diamond I
    December 28, 2022

    ... or would you rather prefer some kind of pencil drawing the curve

    SiCi-Spiral2.gif

    For a constant speed we would need a different parameterization

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