symbolic variable - proving positive

Hi everyone. How can I prove that a symbolic variable is positive? It is not possible to use if statement for symbolic variables.

close all
clear all
a=sym('a','positive');
if(a>0)
    disp('OK')
else
    disp('KO')
end

Thank you.

Answer 1

[Walter Roberson]

syms a positive
if isAlways(a>0); disp('OK'); else disp('KO'); end

https://www.mathworks.com/help/symbolic/isalways.html