Small Solver Program

[Thomas Klemm]

(02-17-2019 02:57 AM)Gamo Wrote:  I just fine tune this solver program for HP-11C

Your program doesn't work for this simple example: \(x^2+x=x(x+1)=0\)
I've entered the following program:

Code:

LBL B
1
RCL 1
+
LSTx
×
RTN

Example:

-2
ENTER
-0.5
A

9.999999 99

The reason is that the function value is divided by -0.5, making it larger and larger:

Code:

LBL 1  // Solver Routine
RCL 0
÷
CHS
RCL 1
+
RTN

---

Another thing is this in this loop:

Code:

LBL 0
GSB B
GSB 1
STO 1
GSB B
GSB 1
RCL 1
X=Y  // End if Root is found
GTO 2
DSE  // Loop Limit Counter
GTO 0

When you return to label 0, the same value in register 1 will be used as before.
This function evaluation can be avoided if you save the result of the previous evaluation.

---

You could move this block:

Code:

LBL 2
RCL 1  // Answer 
RTN

Over here and avoid the jump GTO 2:

Code:

CLx
FIX 9  // 0.000000000 indicate that Maximum Loops is use up.
PSE
PSE
FIX 4 
LBL 2
RCL 1  // Answer 
RTN

---

Take a look at Csaba's solution for the HP-12C using the secant method.

Cheers
Thomas