Getting 3 zeros from a function using fzero

I'm trying to collect the 3 zeros over the interval [-5,5] for the function in my code below. I can't seem to figure out how to used the fzero function so I can collect all three zero values and store them.

my_function = @(x) (-x^2 - 5*x - 3 + e^x);
a = fzero(my_function,[-5 5]);

Answer 1

[Ashikur]

Try this

my_function = @(x) (-x^2 - 5*x - 3 + exp(x));

for i = -5:.01:5

    a = fzero(my_function,i)
    ind = int8((5.01+i)*100) 
    b(ind) = a;
end

result = unique(b)

Note: fzero outputs only one value, and the limit must evaluate the function +Ve and -Ve in the limiting edges. So you have to try a loop.

[D]

Thanks, I was hoping to find a way without for loops, but if it works, it works. I went with the following to get the 3 zeros stored in a single array.

for i = -5:.02:5

a = fzero(my_function,i);

if (b(end) == 0) && (b(end) ~= a)

b(length(b)) = a;

elseif (b(end) ~= a) && (abs((b(end) - a)) > .1)

b(length(b) + 1) = a;

end

end

Answer 2

[Fangjun Jiang]

Are there three zeros? I only get one. Use exp(x), instead of e^x

>> my_function = @(x) (-x^2 - 5*x - 3 + exp(x));
a = fzero(my_function,[-5 5])
a =
  -4.306510588580705

[Ashikur]

This is not what he asked for, I think he is looking for all the solution in that limit. My solution is in below.

[Walter Roberson]

There are 3 zeros,

-.5426539024,

3.482467600,

-4.306510589

Remember, fzero stops when it finds a single zero.

[Fangjun Jiang]

That is good to know. I didn't spend time on it. I thought the OP could get there after passing the e^x error.