I have a field that contrains a hex-string representing an encoded-float number (sign+exponent+mantissa).
What would be a (nice) way of evaluating it into another field that would contain the actual float value?
PS: I can't change the original hex-string.
Show us the sample data and the field and what the sample data should look like after conversion.
You could use a scripted lookup with a small python script doing conversion
external_cmd = hex_converter.py hexstring floatnum
fields_list = hexstring , floatnum
You can after use it with (if number_hex is your field)
| lookup hex_converter hexstring AS number_hex
And you can run it automatically if you want see (automatic lookup)