how can i change x to (x+h)?

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Bishwam Pattnaik
Bishwam Pattnaik 2019-3-12
评论： Steven Lord 2019-3-12
This is my function, f(x)=x^2 - 4 and f(x+h)=(x+h)^2 - 4
f=@(x) x.^2- 4;
f=@(x+h) x.^2- 4 (this gives me error)
How can i write f(x+h) ?

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采纳的回答

Star Strider
Star Strider 2019-3-12
I am not certain what problem you are having. You have to define all the values you pass to your function as arguments before calling your function.
Example —
f = @(x) x.^2- 4;
h = 1E-8;
dfdx = @(f,x,h) (f(x+h) - f(x))./h;
x = 4;
fval = f(x)
derv = dfdx(f,x,h)

更多回答（1 个）

Adam
Adam 2019-3-12
编辑：Adam 2019-3-12
It's the same function definition, you just pass in
x + h
instead of
x
assuming you have x and h defined at the point you call the function.
Or you could define
f = @(x,h) ( x + h )^2 - 4
if you prefer.
  1 个评论
Steven Lord
Steven Lord 2019-3-12
Or you could reuse f in defining the next function.
f = @(x) x.^2- 4;
g = @(x, h) f(x+h);
Check that they give the same result on some sample data.
x = 1:10;
h = 1;
y1 = f(x+h)
y2 = g(x, h)

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