Understanding the HP 28S XPON function
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02-25-2017, 12:21 AM
Post: #1
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Understanding the HP 28S XPON function
I guess I don't quite understand the usefulness of the XPON function on the HP 28S for symbolic expressions. I tried to evaluate the expression XPON("X^3") using ->NUM but it returns the error: Undefined Name. How does one, for example, determine the degree of a polynomial expression?
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02-25-2017, 06:40 AM
Post: #2
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RE: Understanding the HP 28S XPON function
XPON is only for real numbers, not algebraic objects. HP 28S RPL does not contain a command that returns the degree of a polynomial. The DEGREE command which does that was introduced into RPL later, in the HP 48G.
<0|ɸ|0> -Joe- |
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02-25-2017, 12:43 PM
Post: #3
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RE: Understanding the HP 28S XPON function
Probably the 50G, Joe. The 49G AUG does not know DEGREE.
(I have only a 48 and a 49, and I never heard of it - but that's not a reliable reference ;-) Cheers, Werner 41CV†,42S,48GX,49G,DM42,DM41X,17BII,15CE,DM15L,12C,16CE |
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02-25-2017, 03:40 PM
(This post was last modified: 02-25-2017 04:00 PM by mbrethen.)
Post: #4
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RE: Understanding the HP 28S XPON function
I wonder if this can be successfully programmed for the 28s? One thought I had is to perform successive differentiation until you end up with a constant? A loop counter could keep track of the number.
Another idea is to evaluate the polynomial using Horner's method (PVAL in the Math Applications reference) and then SIZE the nested list. |
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02-25-2017, 04:40 PM
Post: #5
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RE: Understanding the HP 28S XPON function
(02-25-2017 12:43 PM)Werner Wrote: Probably the 50G, Joe. The 49G AUG does not know DEGREE. The 49G with firmware version 1.19-6 contains a DEGREE function that returns the degree of a polynomial. It's listed in the 49G's built-in CATALOG, and it has a help screen. The 49G AUG is unfortunately missing an astounding number of 49G commands (at least they are missing from its Command Index on pages 427-432), including the following:
<0|ɸ|0> -Joe- |
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02-25-2017, 09:25 PM
Post: #6
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RE: Understanding the HP 28S XPON function
I stand corrected ;-)
At least it's the 49, not the 48 ;-) Werner 41CV†,42S,48GX,49G,DM42,DM41X,17BII,15CE,DM15L,12C,16CE |
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