How differentiate without using any built-in function

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Ethan Jones 2020-3-4

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评论： Steven Lord 2020-3-4

I have the equation for displacement ye=sqrt(t.^2-ft.^2) where ft is a constant and ft is an equation containing x with the array [0:0.001:2*pi], how would you find velocity without using and built in functions. I have tried using a loop and the definition of derivative, however this does not seem to work.

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KSSV 2020-3-4

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https://ww2.mathworks.cn/matlabcentral/answers/508935-how-differentiate-without-using-any-built-in-function#answer_418448

在 MATLAB Online 中打开

YOu calculate your array by substituing the required values...and use

dy = diff(ye)/dt ; % where dt is step size

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Ethan Jones 2020-3-4

Ok, thanks for the help ; ).

Steven Lord 2020-3-4

diff is nothin but:

which would still violate the rules of the assignment, technically, if for no other reason than the - operator is just another name for the minus built-in function.

If the professor wants to prohibit any built-in function there's not that much you can do (without cheating by writing a MEX-file or something similar.) If they want to be more specific and prohibit certain built-in functions that's potentially a fairer question (depending on what they disallow.)

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