Why do I get error when using a simple global variable?

I get error and it says ''Invalid expression. When calling a function or indexing a variable, use parentheses. Otherwise, check for mismatched delimiters''

global a b t E nu

GP1=(-a/(sqrt(3),-b/(sqrt(3))

GP2=(a/(sqrt(3),-b/(sqrt(3))

GP3=(a/(sqrt(3),b/(sqrt(3))

GP4=(-a/(sqrt(3),b/(sqrt(3))

Answer 1

[Chunru]

Not sure what the code is trying to do. However, the error is due to the wrong usage of ( ) rather than global variables.

global a b t E nu
a=1; b=2; t=3; nu=4;

GP1=[-a/sqrt(3),-b/sqrt(3)]

GP1 = 1×2

-0.5774 -1.1547

GP2=[a/sqrt(3),-b/sqrt(3)]

GP2 = 1×2

0.5774 -1.1547

GP3=[a/sqrt(3),b/sqrt(3)]

GP3 = 1×2

0.5774 1.1547

GP4=[-a/sqrt(3),b/sqrt(3)]

GP4 = 1×2

-0.5774 1.1547