Definition df-relog 14318

Description: Define the natural logarithm function. Defining the logarithm on complex numbers is similar to square root - there are ways to define it but they tend to make use of excluded middle. Therefore, we merely define logarithms on positive reals. See http://en.wikipedia.org/wiki/Natural_logarithm and https://en.wikipedia.org/wiki/Complex_logarithm. (Contributed by Jim Kingdon, 14-May-2024.)

Assertion

Ref	Expression
df-relog	|- log = `' ( exp |` RR )

Detailed syntax breakdown of Definition df-relog

Step	Hyp	Ref	Expression
1		clog 14316	. 2 class log
2		ce 11652	. . . 4 class exp
3		cr 7812	. . . 4 class RR
4	2, 3	cres 4630	. . 3 class ( exp |` RR )
5	4	ccnv 4627	. 2 class `' ( exp |` RR )
6	1, 5	wceq 1353	1 wff log = `' ( exp |` RR )

This definition is referenced by:  dfrelog  14320  reeflog  14323