Hi
Thanks for your time
I want to calculate the Einstein tensor for a metric which is dependent on Z ( in cylindrical coordinate ) and the function is piecewise I wrote this expr :
h = Piecewise[{{-z[] + c, z[] < -1}, {A*z[] + L*z[], -1 <= z[] <= 1}, {z[] + c, z[] > 1}}]; ( c,A,L are Constants )
When I run it I get unknown expr error I don't know what is unknown I have defined everything.