Thomas Dean

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15 years, 61 days

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These are replies submitted by Thomas Dean

@acer 

Sorry for the omission, but, it did not relate to my original question.

That is: How do I manipulate the expression

y = (sqrt(x) + 10)^(1/3) - (sqrt(x) - 10)^(1/3);

into

y^3 = 20 - 3*(x - 100)^(1/3)*y;

or

y^3 = 20 - 3*(x - 100)^(1/3);  ( I think not possible, except at a specific point)

eq1 := y^3 = 20 - 3*(x - 100)^(2/3);

I can not get from

y = (sqrt(x) + 10)^(1/3) - (sqrt(x) - 10)^(1/3);

to

eq2 := y^3 = 20 - 3*(x - 100)^(1/3)*y;

or, to eq1.

The original problem was for a specific x, x=108.

solve(subs(x=108, eq1),y);

2, -1 - 3    I, -1 + 3    I

solve(subs(x=108, eq2),y);

2, -1 - 3    I, -1 + 3    I

Strange!

@Kitonum 

I got turned around on this and now can not get it straight.

restart;
n:=expand((x-1)*(x-2)*(x-3)); ## zeros
d := solve(n/d = 2-x,d); ## oblique asymptote
eq := n/(d-2); ## why is the denominator off by 2?

plot([eq,2-x], x=-4..8, -5..5,  linestyle=[1,3],color=[red,blue], thickness=[2,0], scaling=constrained);

 

@acer 

Sorry I did not provide the example first.

But, my question was not about the example, but, in finding documentation about the syntax.

I played with the example and understood what it did.

I wanted to discover where things like [a,b](c,d) were documented, hoping I would learn about more things like this.

I guess my question should have been what does maple do when two delimiters, one closing and one opening are adjacent in the input stream.  But, I could not make that link.

Sorry.

@Carl Love 

Other than reading all the help pages, how do I find useful things like this?  I looked in the user manual and programming guide.  Evalapply is in neither.

Tom Dean

@Carl Love 

Sort of an Undocumented short cut?

@acer 

From an earlier answer to a question:

P:=x->x^4+x^3+a*x^2+sqrt(2)*x+b;

[Re,Im](P(1+I)); ## in

solve(evalc([Re,Im](P(1+I)))=~[0,0]);

Looking at this, it behaves like map in that [Re,Im](P(1+I));  returns a list of

    [Re(P(1+I)), Im(P(1+I))]

@acer 

It appears that maple2019 does not like subscripted variables as parameters.

restart;

p[D] := r[D] -> 3*r[D];

 invalid parameter; functional operators require their parameters to be of type symbol or (symbol::type)

@Thomas Richard 

I just upgraded to maple2019, the default release then.  Now that maple2020 is released, Maplesoft promised a free upgrade, since I just upgaded to 2019...

For now, I get FAIL.

@Thomas Richard 

This is a long chain of questions/answers, starting in maxima.

If I use enough points, maple produces the most correct plot.

I use maple for most things.

f:= 2*x^5-x^3*y+2*x^2*y^2-x*y^3+2*y^5;
for idx to 10 do
    lim:=1/idx:
    plots[implicitplot](f,x=-lim..lim,y=-lim..lim);
end do;

for idx to 10 do
    lim:=1/idx:
    plots[implicitplot](f,x=-lim..lim,y=-lim..lim,numpoints=1000000);
end do;

 

@Kitonum 

Thanks,

After you pointed the way, I can manually factor f.  Programmatically?

Other than inspection, how do I determine the sign of a group of terms?

@acer 

interface(ansi=false) in .mapleinit fixed the problem.

Thanks

I use linux and command line maple 2019, running in an xterm, with courier 12 font.

When I type, for example, a 'y', it looks like a courier 'y'.  If I then press a space bar, the character changes, so it looks more like a 'u' with an underscore.  If I do this in an xterm not running maple, the character remains looking like a courier 12 'y'.

This echoed character must be coming from maple.

How do I fix this?

I use Maple 2019 and have not seen this.

How long does it freeze?  Is it just busy?  How about CPU usage?

I recently browsed through the maplesoft applications.  I poined it out, hoping it would help.

Maybe someone will be able to help tomorrow or Monday.

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