Tandy 1000 Basic Reference Manual page 214

Chapter 10 I
BASIC
Keywords
LOG
Function
LOG( number)
Returns the natural logarithm of
number.
Number
must be greater than zero. LOG is the inverse of the
EXP
function.
BASIC always returns the result as a single precision number.
Examples
P R I N T LOG(3.14159)
prints the value 1.144729
Z
=
10 LOG(PS/Pl)
performs the indicated calculation and assigns the value to
Z.
Sample Program
This program demonstrates the use of
LOG.
It utilizes a formula
taken from space communications research.
5 4 0 I N P U T " D I S T A N C E S I G N A L M U S T T R A V E L (MILES)";
D
5 5 0 I N P U T "SIGNAL F R E Q U E N C Y (GIGAHERTZ)".
F
5 6 0
L
=
9 6 . 5 8
+
( 2 0
*
LOGCF))
+
(20 LOiCD))
5 7 0 P R I N T "SIGNAL S T R E N G T H L O S S
I N
F R E E S P A C E
IS"
L
"DECIBELS."
212