Clarification on HP-35S Derivative program, please

[Matt Agajanian]

Hi all.

In an earlier post:

HP-35S Calculating Derivatives

the listing is a little unclear.

LBL D
INPUT X
STO C
-->XEQ 001 (what label is the branch target)
STO F
(EQN) 1E-10
STO D
STO+X
X<>Y
XEQ F001
RCL -F
RCL /D
R up
RCL -D
STO X
R down
XEQ F 001
RCL -F
RCL /D
+/-
X<>Y
RTN
STO A
RCL xC
+/-
RCL +F
STO B
RCL A
+/-
1/X
STO E
RCL xC
R up
-
+/-
STO G
(EQN) [A,B]
STO D
(EQN) [E,G]
STO F
RCL D
RCL F
RTN