HP -32S Owner's Manual page 194

results produced by the computer are often preventable by careful
software design. Example 4 illustrates the numerical problem that is
avoided by this quadratic-formula program.
Program Listing:
Program Lines:
Q01 LBL Q
Q02
INPUT fl
Q03
x = 0?
Q04 GTO Q
Q05 INPUT B
Q06 INPUT C
Q07 x=0?
Q08 GTO Q
Q09 RCL B
Q10
+•-
Qll CF 0
Q12 X<0?
Q13 SF 0
Q14
RCL B
Q15 X*
Q16 4
Q17
RCLx fl
Q18
RCLx C
Q19
-
Q20
x<0?
Q21 GTO I
Q22 SQRT
Q23 FS? 0
Q24
+/-
Q25
+
Q26 2
Q27
*
Q28
RCL* fl
Q29 STO X
Description:
Defines the beginning of the quadratic-
equation routine.
Prompts for and stores the value of A.
If A is zero, goes back and asks for A again.
Prompts for and stores the value of B.
Prompts for and stores the value of C.
If Cis zero, goes back and asks for all inputs
again.
Recalls B.
-B.
Clears flag 0. (Assumes that (—B) is
positive.)
Is (—B) negative?
Sets flag 0 if it is.
Calculates B2.
Calculates B2 - 4AC
Tests to see if the roots are imaginary.
Branches to imaginary routine if they are.
V(B2 - 4AQ.
Tests to see if (—B) is negative.
Selects root of largest absolute value.
-B - V(B2 - 4AQ or -B + V(B2 - 4AQ
Calculates X of largest absolute value.
Stores value of X with largest absolute
value.
192 12: Mathematics Programs