Don't forget that you have to escape special characters like the comma:
Note that exponentiation is relatively CPU-costly; if either or both parts of the pow() function are constant, it may be worth the effort of using a precalculated value. There are also some special cases (for instance, non-negative integer exponents) where there are simpler functions you might want to use.
Thanks for your reply and explanation.
In fact I have a big list from ocean sensor, with lot of various number and exponential values...
7.3439156e+005 6.6591366e+000 -8.8263154e-001
7.3439156e+005 6.6961372e+000 -5.6900889e-001
7.3439156e+005 6.6881377e+000 -9.6660798e-001
1st I used "regexp" to "unpack" it
and Now I can make a new list with "real" value... using expr...
I find a problem on my tree !
I used regexp for "unpack" my value : 7.3439156e+005
if function is positive i have a list : 7.34... e +005
but if function is negative (7.3439156e-005) i find : 7.34... e -5 ( zero disappear ???)
next for formatted exponent (+005) i used a another regexp to have 5.
but with the expression I used -5 become also 5
For expr I need 5 (if positive) and -5 (if negative) ( he don't like +5)