Radio Shack TRS-80 User Manual page 219

Exponentiation
Computes:
X
Y (X
to
the
Y
power)
Input:
X,
%
If
X
is
less
than
zeso,
Y
must be
an
odd
integer
Output: P
Also
uses:
E, L, A, B,
C
internally.
Value of
X
is
changed.
Other subroutines required:
Log and Exponential
How
to
call:
3012(9
Logarithms (Natural
and
Common)
Computes:
LOG(X)
base
e,
and
LOG{X)
base
10
Input:
X
greater
than or equal to zero
Output:
L
is
natural log (base e),
X
is
common
log (base 10)
Also
uses:
A,B,C
interally.
Value
of
X
is
changed.
Other
subroutines required:
None
How
to call:
GOSUB
30190
Exponential
Computes:
EXP
(X)
(e to the
X
power)
Input:
X
Output:
E
Also
uses:
L,A
internally.
Value of
X
is
changed.
Other
subroutines required:
None
How
to
call:
GOSUB
30250
30000 END
30100 REM *EXPONENTI ATION* INPUT X,Y
t
OUTPUT
P
30110 REM ALSO USES
E
,
L
,
A
,
B
,
C
INTERNALLY
30120
P=l
:
E = 2
j
IF Y = T.
RET.
30130
IF
(X<0)*( INT( Y)=Y1 T.
P=l-2*Y+4*
INT[
Y/2
) t
X =
-X
33140
IF
XO0
T. GOS.
30190
t
X = Y*L
:
GOS. 30250
32150 P =
P*E
:
RET.
30000 END
30170 REM *NATURAL
&
COMMON
LOG* INPUT X.
OUTPUT L,X
30175 REM
OUTPUT
L
IS
NATURAL
LOG,
OUTPUT
X IS
COMMON LOG
30180 REM ALSO USES A.B.C INTERNALLY
30190 E=0
:
IF
X<2
T. P.
"LOG
UNDEFINED AT"
jX:STOP
30195
A=l
i
B =
2
:
C=.5
32200
IF
X>=A
T.
X=C*X
:
E = E
+ A
:
G.
30200
30205
IF
X<C
T.
X=B*X
:
E=E-A
:
G.
30205
30210 X=(X- ,707127)/{ X+ .707137
) :
L =
X*X
30215
L=C({
,598979*L+. 961471 )*L+2.88539)*X+E-. 5)*,
693147
30220
IF
ABS(LXlE-6
T. L =
30225 X=L*.
4342945
:
RET.
30000 END
32240 REM
*
EXPONENT
I
AL* INPUT
X,
OUTPUT
E
30245 REM ALSO USES L,A INTERNALLY
32250 L=INT(
1
.
4427*X)+1
:
IF
L<127
T.
30265
32255
IF
X>0
T.
P.
"OVERFLOW "
:
STOP
30360 E=0
:
RET.
30265
E=
.693147*L-X
:
A=
1
.
3
29
B
8E-
3-
I
.
4
1
3
1
6E-4
*E
30275 E=(((A-. 166665)* E+. 5)*
E-1)*E+1
:
A=2
30280
IF
L<=0 T. A=
.
5
i
L=-L
:
IF
L=0
T.
RET.
30285
F.
X=l TO
L
:
E=A*E
:
N.
X
:
RET.
217