[pstricks] declare variable and initialize with a value

[Doris Wagner]

hi list,

I have a picture and in this picture a terrible coordinate which I have 
to use often, for example the square root of 2.
How can I avoid always typing 1.4142...? (And how many digits does 
PostScript take, by the way?)
is there something similar to

double x=1.41421356;

such that I can use x in the code, for example \psline(1,1)(1,\x)
???

tia
doris