I'm trying to do some basic trigonometric partial derivatives in Mathematica, and for some reason it is switching my subtraction terms inside the Cos or Sin and giving me an incorrect answer. Why is it doing this? Thanks~
I still don't see what is incorrect.
In:= D[Cos[x - c t], t]
Out= -c Sin[c t - x]
Cos is an even function. What is incorrect about the answer?
Well what ends up happening is when I take the partial derivative of the function (with respect to t), it gives me the wrong (negative) derivative because the inside terms have switched signs.