Undefined operator '>' for input arguments of type 'function_handle'. Error in simple_nlr (line 24) while err > tol

clear all; close all; clc;

%Non Linear Regression

%Model: y = a1*a2^x

%measured data

xm = [50 450 780 1200 4400 4800 5300]';

ym = [28 30 32 36 51 58 69]';

if length(xm) ~= length(ym)

disp('error : xm and ym datasets have different sizes')

end

%define tolerance

tol = 1e-5;

%make intelligent initial guess

a0 = [1 1]

%compute function y

y = @(a) a(1)*a(2).^xm

err = @(a) sum((y(a) - ym).^2)

while err > tol

yopt = fmincon(err,a0);

end

%plots

plot (xm,ym,'ro')

hold on

plot (xm,y,'bx')

Please tell me how to rectify this error and to avoid future mistakes

Answer 1

[KALYAN ACHARJYA]

The err in your code is function handle

>> err
err =
  function_handle with value:

    @(a)sum((y(a)-ym).^2)

You are trying to compare it with numeric value (tol), read about compare function handle

Answer 2

[Steven Lord]

You don't want to ask if the function handle is greater than a certain value.

You want to ask if the result of evaluating the function handle at a certain point is greater than a certain value.

fh = @sin;

thisWillError = fh > 0.5

thisWillWork = fh(pi/2) > 0.5