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    For the function y = e^-x cos2 x work out the value of
    dy/dx at x =1 using
    (a) forward Euler approximation,
    (b) backward Euler approximation,
    (c) central difference approximation.

    Use a step size of (i) delta x = 0.1 and (ii) delta x = 0.01.

    So I know the formula for the Forward Euler is
     \frac {dy}{dx} = \frac {y_{i+1} - y_{i}}{\delta x}

    But don't know what the next steps would be?
    Thank you
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    y_i = y(i \Delta x)

    Plug in values for y_1, y_0, \Delta x
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    (Original post by SimonM)
    y_i = y(i \Delta x)

    Plug in values for y_1, y_0, \Delta x
    Thanks, how do I know what the values for y_1, y_0 are ?
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    (Original post by mh1985)
    Thanks, how do I know what the values for y_1, y_0 are ?
    SimonM's post is assuming you're looking for the value of dy/dx at x=0, and needs modifying for your question.

    y_0=f(1)

    y_1=f(1+1\Delta x)

    Edit: where f is your function e^-x cos2 x.
 
 
 
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