how to remove error"Conversion to logical from sym is not possible."?

i make a fuction that take anynomous fuction as input with value ,

the fuction perform leftsum and definate integral if ' tol' value that is varialble take value from input lies between the value of left sum and integral the it generate the output 1 otherwise 0

i have made that code

function output=myleftcheck(f,a,b,n,tol)
syms x
    dx=(b-a)/n;
    % initialize r to f(a) (the left-end point of the first sub-interval
    % [a,a+dx])
    r=0;
    % need only consider the n-1 remaining sub-intervals
    for k=0:n-1
      c=a+k*dx;
      r=r+f(c);
    end 
    t=dx*r;
    o=int(f(x),a,b)
    p=vpa(o)
    if p < tol >t
output=1    
    else
        output=0
    end
    

the following error is coming,how i should debugg the error

 >> myleftcheck(@(x) sin(x),0,3.14,10,0.1)
 
o =
 
1 - cos(157/50)
 
 
p =
 
1.999998731727539545285114306345
 
Conversion to logical from sym is not possible.

Error in myleftcheck (line 15)
    if p<= tol >=t || t<=tol>=p

Answer 1

[Steven Lord]

This doesn't do what you probably think it does or want it to do.

p<= tol >=t 

This is the same as:

(p<= tol) >=t 

which would be equivalent to one of the following two expressions if p, tol, and t were all numeric variables.

0 >= t
1 >= t

If you want to ask if tol is greater than or equal to both p and t:

(p <= tol) & (tol >= t) % or rewriting
(p <= tol) & (t <= tol)

If you want to ask if tol is between p and t:

(p <= tol) & (tol <= t) % And similarly if p could be greater than t
(t <= tol) & (tol <= p)

But the fact that symbolic variables are involved complicates matters. [For general symbolic variables x and y, is x >= y? The answer in this context is "It's impossible to say."] One solution is not to use symbolic variables. Use integral to integrate your anonymous function numerically rather than evaluating your anonymous function at the symbolic variable x and using int to integrate it symbolically.

f = @sin;
numericAnswer = integral(f, 0, pi/2)
syms x
fs = f(x);
symbolicAnswer = int(fs, 0, pi/2)

When I run those lines of code the answers I receive are:

numericAnswer =
    1.0000
 
symbolicAnswer =
1