I am trying to ask the user for a function of x that can be used subsequently in the code. I tried to use str2func but that is throwing an error

str = input('Give a function to minimize in x: ','s')  ;

f = "@x" +str; %%str2func(['@x '.*str]) ;
f = str2func(f);


%%Initializations                           
gr=double(0.5*(sqrt(5)-1));      % golden ratio
iter=0;                            %iteration counter


%%Initial Calculations
x1=l+(1-gr)*(u-l);
x2=l+gr*(u-l);
y1=f(l);
y2=f(u);

Answer 1

[Matt J]

f = "@(x)" +str;

[Ariit Sengupta]

Thank you so so much @Matt J!! That resolved it