Definition df-e 11993

Description: Define Euler's constant _e = 2.71828.... (Contributed by NM, 14-Mar-2005.)

Assertion

Ref	Expression
df-e	|- _e = ( exp ` 1 )

Detailed syntax breakdown of Definition df-e

Step	Hyp	Ref	Expression
1		ceu 11987	. 2 class _e
2		c1 7928	. . 3 class 1
3		ce 11986	. . 3 class exp
4	2, 3	cfv 5272	. 2 class ( exp ` 1 )
5	1, 4	wceq 1373	1 wff _e = ( exp ` 1 )

This definition is referenced by:  esum  12006  ere  12014  ege2le3  12015  efzval  12027  reeff1oleme  15277  loge  15372  logdivlti  15386