Question

I have the logarithms of very large values, for example:

log_a = 1347 
log_b = 1351 

And I am trying to solve this expression:

exp(log_a) - (0.1 * exp(log_b))

Or equivalently this (same expression just in a different form):

exp( log_a ) - exp( log(0.1) + log_b ) 

But of course every time I try to compute exp(log_a) or exp(log_b)
values I get Inf. Are there any tricks I can use to get a real result
for exp(log_a) – (0.1 * exp(log_b)), either in logarithm or
exponential form?

Thank you very much for the help!

Answer 1

library(Brobdingnag)
a <- as.brob(exp(1))^1347
a*(1-0.1*exp(4))
#[1] -exp(1348.5)

or calculated manually:

-(exp(1347+log(0.1*exp(4)-1))=-exp(1347+1.4951...)=-exp(1348.4951...)