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-   -   Calculating slope and change in slope (Mathcad) (https://www.askmehelpdesk.com/showthread.php?t=159473)

  • Dec 5, 2007, 03:05 AM
    jeepey
    Calculating slope and change in slope (Mathcad)
    Hello, I have been using mathcad for a only a few weeks, so my knowledge of it is limited.

    I have a set of data points which I have created some polynomial and cubic splines on a graph.
    What I want to do is calculate the slopes and change in slope of the curves.

    Any help on a mathcad function that can do this would be appreciated, I was hoping I could attach my mathcad work sheet but won't let me attach the file :(

    Thanks in advance :cool:
  • Dec 5, 2007, 09:49 PM
    mathcad
    If you have created the polynomial or interpolating function, you can just use the first derivative operator (click on the calculus icon/toolbar) to get the slope and use the second derivative operator to get the rate of change of the slope.

    For example:

    Suppose you have two sets of data vx and vy and you create the interpolating function by using cubic spline and interpolation:

    vs:=cspline(vx,vy)
    y(x):=interp(vs,vx,vy,x)

    Then the slope is

    s(x):=d/dx y(x)

    The operator d/dx must be obtained from the calculus toolbar, you can't just type d/dx. The slope at any point can be calculated easily, for example at x = 2, just type s(2) and the equal sign.
  • Dec 5, 2007, 11:41 PM
    jeepey
    Thank you very much for your help,
    That's worked a treat!

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