saving variables in a for cicle

[oceanografo]

How can I save variables in a for cicle.
An example:

for i=1:12
P=x(i)
save 'value(i).mat' P
end

How can I get that the file value will be altered with the value of i
Example:

for i=1 => P=1 => value1.mat
for i=2=> P=2 => value2.mat

Thanks

João