multiplication of functions integration problem

Hello,i have two functions "fun" and "coef_fun"

"coef_fun" was created with interpolation of the attached CSV and it looks like in the photo bellow.

I have integrated fun over some interval ,and i got some numeric result.

When i tried to integrate the multiplication of fun and coeff_fun (in order to see the reduction the the numeric result)

It gives me an error "Undefined operator '*' for input arguments of type 'function_handle'"

i have attached my code.

Where did i go wrong in integrating multiplication of functions?

Thanks.

%Default Dataset_new file
data = load('Default Dataset4.csv');
x = data(:,1);
y = data(:,2);
%plot(x,y);
data_x1=x*0.000001; %transform to micron
[data_k, index] = unique(data_x1); 

Answer 1

[ChrizzzlP]

mult_fun needs to be defined as a function too. simple example below:

fun = @(x)x+3;
coef_fun = @(x) 5*x+9;

multiplication_func = @(x) fun(x)*coef_fun(x);

multiplication_func(2)

[Steven Lord]

You can't multiply function handles.

multiplication_formula = @(lambda) fun*coef_fun;

You can multiply the values you receive when you evaluate function handles.

multiplication_formula = @(lambda) fun(lambda).*coef_fun(lambda);

I switch to using element-wise multiplication (the .* operator) instead of the matrix multiplication operator (the * operator) because I see you're passing this function handle multiplication_formula into integral. Generally you want to use the element-wise operators in functions you're going to pass into integral, ode45, and similar functions.

[fima v]

Hello Steven when i did the "fun" ONLY integration,fun_integral results in 43

But when i integrate the element wise multiplication you suggested( which is adding a filter and it should reduce the integral result)instead i get NAN in the mult_integral.

it said "Warning: Infinite or Not-a-Number value encountered"

Why my integral exploded?

What could be done?

Thanks

data = load('Default Dataset4.csv');
x = data(:,1);
y = data(:,2);
%plot(x,y);
data_x1=x*0.000001; %transform to micron
[data_k, index] = unique(data_x1); 

[fima v]

Hello I was able to integrate the Purple plot over the range and it gave me 43

Why when i integrate the smaller green plot My integral explodes?

Thanks.