Trig Func Plot Error and Trig Solving Error

[Bosebcc]

(10-29-2019 06:13 PM)Tim Wessman Wrote:  

(10-29-2019 02:22 PM)Bosebcc Wrote:  - Even though using solve(cot(x)^2 + 3*csc(x) = 3,x,0..2pi) doesn't display the 1.57 solution,

Erm? What is the 1/2*pi you are showing?


Also, for that plot you show, try checking the "allow complex output from real input" in page 1 of Home settings.

Quote:[5] Why can't the advance graphing app display a correct graph for many fcns.

Such as?

Thank for your reply it have been very helpful. First of all checking "allow complex output from real input" did the job for the graph in the function app. I am still confuse why the advance graphing app show two line. Maybe it's a limitation of the graphing engine(http://www.peda.com/grafeq/) or I have some setting on which cause the result.

(10-29-2019 09:12 PM)pinkman Wrote:  Like Tim I also don’t understand why you say x=pi/2 is not an intersection of your previous f(x) with g(x)=3, because CAS found it : [1/2*π,-asin(1/4),asin(1/4)-π]

Regards.
Thibault

//1 For the pi/2 result, I do understand see that that is the solution. But it still doesn't explain why fsolve or solve can't show all the solution in the interval. I'm sorry that I didn't provide a clear example that indicate the problem. For example the interval 2pi..4pi for the same function. In the hp prime using solve(cot(x)^2 + 3*csc(x) = 3,x,2pi..4pi) It returns 9.677, 12.313 instead of 7.854, 9.677, 12.313

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(10-30-2019 02:20 AM)Tim Wessman Wrote:  Oh, I forgot to mention - if you want the general periodic solutions like 2*n, uncheck the ""principal solutions" check on page 1 of the CAS settings page. I think that does what you are looking for.

As to why the "allow complex result from real input" checkmark makes a difference here, you have (-X)^(-X)|X<0 power which does not have a non complex result. Since many teachers want negative exponents to "error" until they are ready to teach about it, this is the default setting.

//2 Thank you for this too. I have one question about the output of principal solution. In the result of the periodic solution, it includes n_2,n_3,n_3. I have not seen this notation before. Is this the notation for interger and is n_2 the same as n_3?

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(10-28-2019 07:53 AM)FrankP Wrote:  

Quote:[1] Why is there a asymptote for some graph and not for others?

Well, even the internal representation of the relation

Y=1/(X-1)+2/(X-1)

in the Advanced Graph App on my Android Emu decides to draw a vertical line on the definition gap X=1. But no line at X=1 for

Y=1/(X-1)+1/(X-1)

!?? Strange.
But maybe an acceptable workaround could be drawing the result of the CAS command collect of the function? So in your case:

collect(cot(x)^2+3*csc(x))

The result

(1+3*sin(X)-sin(X)^2)/sin(X)^2

has no assymtote anymore.

//3 That solves the problem for this function but there is another problem. Yesterday I found a function while doing a problem that had the same issue(asymptote appearing)
and I tried to use the collect function but this time the asymptote didn't go away. [I can't find the function, I will try to find it and post an update]