does double() work on UNIX?

[mkapadia]

I have a task of migrating scripts from SunOS to Linux, tehre is a
.awk file, which has a function double

e.g
double(substr("abcwertert", 7,1));
it works perfectly on SunOS but on Linux it says,

awk: test.awk:6: fatal: function `double' not defined

please help

thank you

[ghostdog74]

it should be a user defined function in awk from Solaris version.
show the whole code if you can

[mkapadia]

sym = substr($0,1,11);
if (sym ~ /\t/) sym = sprintf("%-11.11s",substr(sym,1,index(sym,"\t")-1));
Symbol [ symcounter ] = sym;
SymbolStatus [ sym ] = 1;
BaseValue [ sym ] = double(substr($0, 12,length-11));