10-17-2017, 08:31 AM

LOGARITHMS FOR ANY BASE

The following keystrokes solve for the exponent c in the equation A^c = B when A and B are known. This procedure may be labeled "finding the logarithm of B to the base A".

The natural logarithm of B will again be available in the y register

Keystrokes:

1. A ENTER 1 - 100 x [i] -1 [PV] B [FV] [N] --------> c

2. [X<>Y] ---------------------------------------------> ln B (base e) "this only work on HP-80"

Example:

Find the exponent c in the equation: 16^c = 4096

1. 16 ENTER 1 - 100 x [i] -1 [PV] 4096 [FV] [N] -> answer 3.00 (log 4096, base 16)

2. [X<>Y] -------------------------------------------> answer 8.32 (ln 4096, base e)

The following keystrokes solve for the exponent c in the equation A^c = B when A and B are known. This procedure may be labeled "finding the logarithm of B to the base A".

The natural logarithm of B will again be available in the y register

Keystrokes:

1. A ENTER 1 - 100 x [i] -1 [PV] B [FV] [N] --------> c

2. [X<>Y] ---------------------------------------------> ln B (base e) "this only work on HP-80"

Example:

Find the exponent c in the equation: 16^c = 4096

1. 16 ENTER 1 - 100 x [i] -1 [PV] 4096 [FV] [N] -> answer 3.00 (log 4096, base 16)

2. [X<>Y] -------------------------------------------> answer 8.32 (ln 4096, base e)