How to declare a function having bounds ?

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David Webb
David Webb 2015-2-8
评论： David Webb 2015-2-9
example-
f(x)= 0 x<0
x 0<x<1
-1 x>1
  2 个评论
David Young
David Young 2015-2-9
编辑：David Young 2015-2-9
What is supposed to happen if x=0 or x=1? I'm guessing you mean
0 if x < 0
x if 0 <= x <= 1
-1 if x > 1
David Webb
David Webb 2015-2-9
function given above is just for example not the actual function. Just wanted to know how to declare such a function.

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采纳的回答

Matt J
Matt J 2015-2-8
编辑：Matt J 2015-2-8
One way,
f=@(x) x.*(x>=0 & x<=1) - (x>1)

更多回答（2 个）

David Young
David Young 2015-2-9
I would go for a vectorised function:
function x = clipZeroOne(x)
x(x < 0) = 0;
x(x > 1) = -1;
end
Test examples
clipZeroOne(9)
clipZeroOne(0.5)
clipZeroOne(-0.5)
clipZeroOne([-Inf -3 0 0.2 0.9 1 15 Inf]) % apply to a vector
Erik S.
Erik S. 2015-2-8
编辑：Guillaume 2015-2-9
function f=fcn(x)
if x<0
y = 0;
else if x>=0 && x<1
y = x;
else if x>1
y = -1;
end
In the example f(0) = x.
  2 个评论
David Young
David Young 2015-2-9
编辑：David Young 2015-2-9
This answer has multiple issues, as they like to say on Wikipedia.
  • What happens if x is exactly equal to 1?
  • The output variable is f but you assign the result to y.
  • "else if" isn't legal MATLAB.
  • The "{} Code" button makes the code display clearly.
I guess what you meant was this
function y = fcn(x)
if x<0
y = 0;
elseif x<1 % it must be greater than or equal to 0
y = x;
else
y = -1; % it must be greater than or equal to 1
end
end

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