Multiple solutions with specific range input

Here is my function: fun(x) = abs(abs(abs(x)-5)-2) and the range of input x: -5~7

If fun(x)= 1, I know the solutions of x are -4,-2,6

But how can I realize it with MATLAB ? Thanks.

Answer 1

[Stephen23]

Actually there are more solutions:

>> fun = @(x)abs(abs(abs(x)-5)-2);
>> foo = @(x)fun(x)-1;
>> x = -5:0.1:7;
>> idx = find(diff([1,diff(foo(x))>0,1])~=0);
>> baz = @(a,b)fzero(foo,x([a,b]));
>> out = arrayfun(baz,idx(1:end-1),idx(2:end))
out =
    -4    -2     2     4     6

And you can see the solutions here:

plot(x,fun(x),'-',out,ones(size(out)),'o')