converting text to float?

Hey,
I'm trying hard to convert text to float, and all i get are 
messages like this:

select float4(wartosc) from  tblwartosci ;
ERROR:  Function 'float4(text)' does not exist       There is more than one function that satisfies the given
argument types       You will have to retype your query using explicit typecasts

select float4(int(wartosc)) from  tblwartosci ;
ERROR:  pg_atoi: error in "285.75": can't parse ".75"

Table    = tblwartosci
+----------------------------------+----------------------------------+-------+
|              Field               |              Type                |
Length|
+----------------------------------+----------------------------------+-------+
.
.
| wartosc                          | text                            
|   var |
+----------------------------------+----------------------------------+-------+

Is there a resonable way to do text to float conversion?

bart
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