Generating a Polynomial Given Its Roots

[Thomas Klemm]

Here's the program adapted for the HP-11C:

Code:

001-42,21,11    LBL A
002-      16    CHS
003-      36    ENTER
004-    22 1    GTO 1
005-42,21, 0    LBL 0
006-      34    x<>y
007-      20    ×
008-   43 36    LSTx
009-      34    x<>y
010-42,21, 1    LBL 1
011-   42 23    x<> (i)
012-44,40,24    STO+ (i)
013-    42 6    ISG
014-    22 0    GTO 0
015-   45 25    RCL I
016-   42 44    FRAC
017-      26    EEX
018-       3    3
019-      16    CHS
020-      40    +
021-   44 25    STO I
022-   43 32    RTN

Example:

CLEAR REG
CLx
STO I
-3 A
3 R/S
4 R/S
6 R/S

The coefficients of the polynomial can be found in the registers:

R 0:  -10.0000
R 1:   15.0000
R 2:   90.0000
R 3: -216.0000

Here as well the leading coefficient is always 1.

Cheers
Thomas