Create Tanget Line

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Wed, 07/20/2011 - 11:34 am

Dear all,

I want to ask who to create a tagnet line from a point of a wave?
Because I want to find the slope of the tangent line.

Thanks
In case you are only interested in the slope, I'd recommend to differentiate the wave.
The Differentiate command is available via the Analysis menu

July 20, 2011 at 01:34 pm - Permalink

If a tangent line on a graph is needed, a little more work is required. Here is a code snippet example using drawing tools:
function DrawTangent(inwave,xpos, arrowscale)
    wave inwave
    variable xpos, arrowscale
    Duplicate/FREE inwave, dinwave
    Differentiate wave0 /D=dinwave
    SetDrawLayer /W=Graph0 /K userfront
    SetDrawEnv/W=Graph0 xcoord= bottom,ycoord= left,arrow= 1, save
    DrawLine/W=Graph0 xpos, inwave(xpos), xpos+arrowscale, inwave(xpos)+arrowscale*dinwave(xpos)
end

This has the feature that resizing the graph will maintain the tangent appearance of the added line. Modify to your taste, and flexibility requirements.
Graph0_1.png Graph0_1.png Graph0_1.png

July 21, 2011 at 07:02 am - Permalink