arrays of anonymous functions

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john4312
john4312 2016년 10월 18일
댓글: Steven Lord 2016년 10월 18일
I want to create an array of anonymous functions in a loop , but all my arrays are becoming empty except for the last one . Please Help ! I have used J =50 ! . Note : If I display the function after each loop evaluation , it works !
function[g]=poly1(J)
xa=-1;xb=1;
dx=(xb-xa)/J;
x=xa:dx:xb;
for i=1:J+1
g=cell(J+1,1);
a=x(i);
a1=a+dx/2;a2=a-dx/2;
a3=[a1,a,a2];
ux=-sin(pi*a3);
y=polyfit(a3,ux,2);
a=y(1);b=y(2);c=y(3);
g{i}=eval(sprintf('@(x) %d*x^2+%d*x+%d',a,b,c));
end
  댓글 수: 1
Steven Lord
Steven Lord 2016년 10월 18일
There is no need to use eval here.
a = 1;
b = 2;
c = 3;
g{1} = @(x) a*x.^2+b*x+c;
I know what you're likely to say -- g doesn't show the values of the coefficients, just the variables. The values of those coefficients are stored in the anonymous function and are used when it is evaluated. And if your coefficients are not exactly integer values, the difference could be important.
a = exp(1);
g{1} = @(x) x+a;
g{2} = eval(sprintf('@(x) x+%d', a));
g{1}(0)-a % should be 0 and is 0.
g{2}(0)-a % should be 0 but isn't 0.

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Adam
Adam 2016년 10월 18일
편집: Adam 2016년 10월 18일
g=cell(J+1,1);
in the first line of your for loop overwrites everything previously in g. Move it outside the for loop instead.
  댓글 수: 1
john4312
john4312 2016년 10월 18일
thank dude ! I miss that

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