Carl Love

Carl Love

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13 years, 122 days
Himself
Wayland, Massachusetts, United States
My name was formerly Carl Devore.

MaplePrimes Activity


These are replies submitted by Carl Love

@Andriy I think that the NAG methods work strictly in hardware floating point, and do not run any differently based on the setting of digits, Digits, or epsilon. Note that they refuse to run at all if digits is greater than 15. I also don't think that there is really any specifically Maple implementation of the NAG method; rather, it is just a call to unmodified external code. If this is true, you should get the same results from any other program that used NAG.

@Majmaj Here are four examples that I hope will improve your understanding. First read through the examples, then go back and read again, this time trying to figure out why each output is the way that it is. After thinking about it for a while, ask me any questions you have if you're still confused.

 

restart:

P:= proc(x) x:= 23; return x end proc:

a:= b:

c:= P(a);

b

a;

23

b;

23

eval(a,1); #One level of evaluation.

b

eval(a,2); #Two levels of evaluation.

23

eval(c,1);

b

eval(c,2);

23

restart:

P:= proc(x) x:= 23; return x end proc:

a:= b:

c:= P('a');

a

a;

23

b;

b

eval(a,1);

23

eval(c,1);

a

eval(c,2);

23

restart:

P:= proc(x) x:= 23; return eval(x) end proc:

a:= b:

c:= P(a);

23

a;

23

b;

23

eval(c,1);

23

#See that c has no connection to a or b in this case!

restart:

P:= proc(x) x:= 23; return eval(x) end proc:

a:= b:

c:= P('a');

23

a;

23

b;

b

eval(a,1);

23

#See that a has lost its connection to b in this case.

eval(c,1);

23

#Nor is c connected to b.

 

Download eval.mw

@ecterrab But can D handle a negative exponent, as is (D@@(-2))? I believe that is what the OP is asking about.

@adel-00 Sorry, it took me a long time to figure out what you are talking about. To extract the beta, for example the 4994., do

Min(mytab2, Val)[1];

Regarding your other question, I still can't figure out what you are talking about.

The error message is about not being able to achieve a certain accuracy. It is not at all surprising to me that rewriting the integrand makes it work. I don't think it's a bug.

@adel-00 Okay, here is a procedure to find the closest point to N'(t) = 0 in mytab2.

Min:= proc(L::{list, set, rtable}, Val)
local x, min:= infinity, v, X;
     for x in L do
          v:= Val(x);
          if v < min then  min:= v;  X:= x  end if
     end do;
     X
end proc:

Val:= x-> abs(x[2]):

Min(mytab2, Val);
       [4994.00000000000, -2.784601937964963e-11]

@adel-00 Your code does correctly produce a table of [t, N'(t)] (although there are easier ways to do this). But N'(t) is never 0, and no matter how you change the parameters, it still will never be 0, for the reason Preben mentioned. N'(t) makes a slow, asymptotic approach to 0 as t approaches infinity.

@John Fredsted Maple is not going to change the user's possibly complex entry by putting Re around it. Since the entry is possibly complex, it just reverts to every Matrix entry's default value of 0. If you want nonzeros on the diagonal, then you'll need to specify explicitly real values for the diagonal.

Since you mentioned quantum mechanics, I've added physics to main post's tags in the hope that Edgardo would comment.

@John Fredsted Maple is not going the change the values of your entries. Consider the difference in the output of the following two commands:

Matrix(3, (i,j)-> i+I*j, shape= hermitian);

Matrix(3, (i,j)-> `if`(i=j, i, i+I*j), shape= hermitian);

@m-Dede Try this

if z=0 then v1:= -1 else v1:= z fi;

@m-Dede I have no idea what you're talking about. Can you give more details?

The book is extremely difficult to read. It has no mathematical typesetting; all formulae are in plaintext, not even in Latex. A huge number of words are   s p a c e d   o u t   l i k e   t h i s.

And I did not notice any Maple content, although, of course, I did not read the whole book.

@J4James I am not aware of any tool to directly put the Maple output into the Excel format, but it looks like you're well on your way to creating the tool yourself. The basic data required is all there in the solution module, as you can see. Statistics has the F distribution and a OneWayANOVA command. Note the you can use CDF instead of integrating the PDF for the t distribution.

@key01023 The matrix is still missing. Can you upload a worksheet?

@J4James Don't use whole numbers; end them with decimal points.

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