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Definition df-logb 13221
 Description: Define the logb operator. This is the logarithm generalized to an arbitrary base. It can be used as logb for "log base B of X". In the most common traditional notation, base B is a subscript of "log". The definition will only be useful where is a positive real apart from one and where is a positive real, so the choice of and is somewhat arbitrary (we adopt the definition used in set.mm). (Contributed by David A. Wheeler, 21-Jan-2017.)
Assertion
Ref Expression
df-logb logb
Distinct variable group:   ,

Detailed syntax breakdown of Definition df-logb
StepHypRef Expression
1 clogb 13220 . 2 logb
2 vx . . 3
3 vy . . 3
4 cc 7713 . . . 4
5 cc0 7715 . . . . 5
6 c1 7716 . . . . 5
75, 6cpr 3561 . . . 4
84, 7cdif 3099 . . 3
95csn 3560 . . . 4
104, 9cdif 3099 . . 3
113cv 1334 . . . . 5
12 clog 13137 . . . . 5
1311, 12cfv 5167 . . . 4
142cv 1334 . . . . 5
1514, 12cfv 5167 . . . 4
16 cdiv 8528 . . . 4
1713, 15, 16co 5818 . . 3
182, 3, 8, 10, 17cmpo 5820 . 2
191, 18wceq 1335 1 logb
 Colors of variables: wff set class This definition is referenced by:  rplogbval  13222
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