A few things, Jonathan... (HP 50g a few questions) Message #8 Posted by Karl Schneider on 27 Apr 2008, 10:33 p.m., in response to message #4 by Jonathan Vogel
This Forum is primarily intended as a place for discussion, not as a "quick free help" message board. (Have you tried comp.sys.hp48?) From the telltale careless and conversational manner in which you have phrased your questions and stated your replies, I would assume that you are a highschool student or college undergrad. Most of us here are middleaged technical professionals. Two of us have graciously addressed your questions; I'm really not quite sure how to characterize your response 
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Ok I have a couple questions
Like I want to find the area bounded by y=5sin(1/2x) and y=3 and y=0 ... (????)
How can I find the area between two curves without setting up an integral? ... But let's just say I was dumb and didn't know how to set up an integral to evaluate this.
...
it still took me 15 minutes to actually figure out what you meant. That could have to do with my intelligence, your explanation, or the 50g's user friendliness. This alone proves my point. A 10 year old can easily graph on the TI83.
Try to do your method and compare it to the (actual) answer because I would get like .97 and the actual answer would be 1.93.
...
Also Karl, I asked to find the area between two curves using the graphing utility to check my answers. I know how to do it using calculus (integrating) and I am pretty darn familiar with the standard integrating capabilities of the calculator but thanks for mentioning that.
Now let me ask something else based on your last two links you sent me.
No one owes you any assistance, so you ought to be more courteous in your requests. Here's another link, which contains some pearls of wisdom:
How to Ask Questions the Smart Way
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How can I find the area between two curves without setting up an integral? ... But let's just say I was dumb and didn't know how to set up an integral to evaluate this.
Until I read between the lines, the basic response that came to mind was along the lines of, "Hypothetically speaking, you should RTFM, and learn how to do it. This is fundamental mathematics."
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I want to find the area bounded by y=5sin(1/2x) and y=3 and y=0 ...
Are you sure that you stated this correctly? What are the limits of x? Are you interested in the positive values of the function that are less than 3? Did you really mean "(1/2x)"  which becomes (positive or negative) infinite as x approaches zero, and can make for a nasty integral that would be difficult to estimate by graphical methods? Or did you mean "(x/2)"?
How exactly should Hal (or I or anyone else, for that matter) obtain your "actual" answer?
The bottom line is, you really ought to invest more in thought, effort, and time to proofread before posting questions that will require time and effort from others to answer.
As you might have gathered from the two archived links of 2004, I'm neither an expert about, nor an enthusiast of RPLbased (HP28/48/49/50) calc's. I also find them difficult to use. I prefer the old, classic RPNbased models (e.g., HP15C/42S/32SII).
Now, as for your other questions:
1. How can I solve ln(x)=x2
I'm having the same difficulties on the HP49G. "SOLVE" or "SOLVEVX" are designed to find symbolic solutions, for which none exist in this problem. Setting flags 03 (numerical result) and 105 (approximate mode) only seemed to force their changing to the appropriate settings for symbolic solutions. These functions can find roots for polynomials, even when the symbolic solutions would be quite complicated (e.g., cubic and quartic). The key here might be "rational", as any polynomial can be factored into linear and quadratic terms (although the quadratic terms might not have any realvalued roots).
A numericsolution stackbased alternative to "NUM.SLV" is "ROOT"
'LN(X)=X2' 'X' 0.5 ROOT
'LN(X)=X2' 'X' 1.5 ROOT
yield the two answers. If "SOLVEVX" fails, you can put 'X' and a random "guess" value onto the stack, and you will likely get a numeric answer. (Curiously, "ROOT" is missing from the HP49G manual, although both the HP48G and HP49G have it.)
The "guess" is used to direct the rootfinder toward the value you seek. There might be other roots that you don't want, or local minima/maxima that may foil the solver. If there is only one root in a monotonic function, the solver will find it, no matter what guess is provided. Rest assured that the solver algorithm (TI's or HP's) will use some guess to start the process...
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Is there a 50g program that will calculate the area between two curves based on the equations in stack 1 and 2?
If you understand what's going on in the RPL program listed in my second link, that's a good template for a simpler one that will accomplish that.
There are RPL experts here who could surely spoonfeed to you what you seek, but that's strictly their prerogative to do so...
 KS
Edited: 28 Apr 2008, 2:44 a.m.
