Hello, in my program I want to calculate the 1st derivative of a function y (it's a function of 'x1'). Let's say I want to check if the 1st derivative of this function in some specific point is smaller then 0.05. I have:
syms x1; y = ( x1 - za )*( x1 - zb )*( x1 - zc )*( x1 - zd ); %my function, all the parameters like 'za' were previously declared
unfortunately the derivative is not calculated. I get information: Warning: 1 equations in 0 variables. Warning: Explicit solution could not be found. and when I try to display dydx_val i get:
I tried different methods, none of them was good (although I could do something wrong). I will be grateful for suggestions how can I calculate 1st derivative in a specific point and have the value of this derivative in double.