Why does matlab change cos / sin input?

Hello,

Something very weird happens when i try to integrate cos / sin functions. Matlab changes te values i put in the cos / sin for example this happens when i want to integrate acceleration (a) to speed (v):

>> syms x

>> a=cos(-2*x+3)

a =

cos(2*x - 3)

How can i avoid this?

[John D'Errico]

Why does it matter at all? cos(X) == cos(-X). So it changes nothing.

[Stephen23]

"Something very weird happens when i try to integrate cos / sin functions..."

Why is it weird? They are exactly equivalent.

Answer 1

[Siriniharika Katukam]

Hi

Assuming that your issue is the change of signs in the "cos" function, the interpreted value of a as cos(2*x - 3) is right as "cos(x) = cox(-x)". You will get the same values when you try to integrate both cos(-2*x + 3) and cos(2*x – 3).