How I should fix this problem with the function evalin?...Help me, please.

function s = eval(x)

if builtin('numel',x) ~= 1,  x = normalizesym(x);  end

s = evalin('caller',vectorize(map2mat(char(x))));

Error using sym/eval (line 11)

Error: Unbalanced or unexpected parenthesis or bracket.

AND

>> sym.eval
The class sym has no property or method named 'eval'.

[Walter Roberson]

What are you passing to the routine?