Why are there different results of 'simplify' function for similar inputs?

Hello, I am using the simplify function for simplifying some equations in Matlab. Basically, it involves getting two symbolic expressions for the x and y components of stress-fields. In my case, the equations are pretty similar and look like this:

and

When I input these expressions to the simplify function, these are the results:

syms br1 bi1 r t;
simplify((br1*((3*cos(t/2))/2 + cos((5*t)/2)/2) + bi1*((7*sin(t/2))/2 + sin((5*t)/2)/2))/(2*r^(1/2)))

ans = 

simplify((br1*((5*cos(t/2))/2 - cos((5*t)/2)/2) + bi1*(sin(t/2)/2 - sin((5*t)/2)/2))/(2*r^(1/2)))

ans = 

My question is, even thought the terms in both equations are mathematically of the same 'complexity', why does the simplify function give different results? Does it have something to do with the way I wrote the equations or is it because the way Matlab stores them internally is different(if so, what)?

(Note: the number of steps in simplify also doesn't seem to affect this result, as taking 100 steps in both cases has the same output as above)

Thanks!!

[Dyuman Joshi]

"... even thought the terms in both equations are mathematically of the same 'complexity'..."

Are they?

Answer 1

[N A POORNA CHANDRA]

hi saketh, i think there is mistake in your equation some where in paranthesis i guess i used the first equation and replaced them it is woring fine here is the updated second equation

simplify((br1*((5*cos(t/2))/2 - cos((5*t)/2)/2) + bi1*((sin(t/2))/2 + sin((5*t)/2)/2))/(2*r^(1/2)))

[Saketh]

Hey Poorna,

The equation that you have given has a wrong sign. The last term has a '+' instead of a '-'. Changing this again gives the previous results, although it is interesting that a single sign change causes this.