Applying a negative to the function to find the maximum

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Gavin Seddon
Gavin Seddon 2015-8-20
回答： siscovic 2017-11-11
hello to find the maximum point in a curve I must use the negative function however this creates errors. My function is f = @(x)p1*x^4 + p2*x^3 + p3*x^2 + p4*x + p5 where does the minus sign precede the f? Thanks.

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采纳的回答

Titus Edelhofer
Titus Edelhofer 2015-8-20
Hi,
your minus should span the entire function, i.e.
f = @(x) -(p1*x^4 + p2*x^3 + p3*x^2 + p4*x + p5);
Titus

更多回答（4 个）

Steven Lord
Steven Lord 2015-8-20
If you don't want to recreate the function handle as Titus suggested, create a new function handle that calls the existing function handle and negates that function's output:
minusF = @(x) -f(x);
Azzi Abdelmalek
Azzi Abdelmalek 2015-8-20 
f=@(x)p1*x^4+p2*x^3+p3*x^2+p4*x+p5
h=@(x)-f(x)
Gavin Seddon
Gavin Seddon 2015-8-21
Many thanks for all these answers; this was what I was after Titus. I will implement your suggestion Stephen. Thank you again.
siscovic
siscovic 2017-11-11
Hello, how to calculate the gradient, Hessian matrix, of this function.Thank you
f=@(x) (x(1)-2)^4+(x(1)-2)^2*x(2)^2+(x(2)+1)^2

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