In connection with this thread about annihilation/creation operators, the issue of a "sum with 'safe' dummy parameter" was presented. In brief, what is the expected output for the following?

> a := 1; b := 2; j := 3

> sum(f(j), j=a..b)

sum interrupts with an error but one can say, with good reason, that the expected output is f(1) + f(2). But then what is the expected output of

> a := 1; b := 2; j := k

> sum(f(j, k), j=a..b)

Say we are happy with f(1, k) + f(2, k), so not f(1, 1) + f(2, 2). Then what is the expeced output of

> a := 1; b := 2; k := j;

> sum(f(j, k), j=a..b)

Say we are happy with f(1, 1), + f(2, 2).

If this is the case then I think we have a design to handle the dummy parameter. In brief: the summation index is not a local variable and use the standard full evaluation rule for everything but for the summation index (note the full evaluation rule would be applied to all of the summand but for occurrences of the summation index - it is tricky to implement but doable).

If we agree with this design, I am anyway mostly sure this would not be implemented within the standard Maple sum (backwards compatibility issues may appear) but, for instance, it could be implemented within Physics, either overloading the standard sum when Physics is loaded, or as a separate Physics:-Library:-sum command, that one could make it to the surface with ease entering with(Physics:-Library, sum).

Solve the following system of equations

The solution to the following differential equations results in empty brackets [] and I want to know their content

> Restart; ode := B*(x-1)^2*(diff(y(x), x, x))+C*(x-1)*(diff(y(x), x))+(A-x/(x-1))*y(x) = 0;


> dsolve(ode);

y(x) = _C1*(x-1)^((1/2)*(-C+B-I*sqrt(-B^2+(2*C+4*A-4)*B-C^2))/B)*hypergeom([], [(B+I*sqrt(-B^2+(2*C+4*A-4)*B-C^2))/B], 1/(B*(x-1)))+_C2*(x-1)^((1/2)*(-C+B+I*sqrt(-B^2+(2*C+4*A-4)*B-C^2))/B)*hypergeom([], [(B-I*sqrt(-B^2+(2*C+4*A-4)*B-C^2))/B], 1/(B*(x-1)))

HERE IS A FUNCTION THAT I WANT TO DIFFERENTIATE

I've been wondering if this is possible and i'd be very happy if it is. Is there a way i can format the output of and fsolve(). in such a way that it does not come in curly braces, preferably, it comes out in a colomn-vector form and without the names of the variables solved for. Just the values. 

Secondly, I've been trying to apply the newtons method for my friend here in school but i've been getting an error message...

Let X be the random variable uniformly distributed in the disk centered at the origin O(0,0) with radius 1 and let Y be the random variable uniformly distributed in the square having its vertices A(6,-1), B(9,-2), C(8,-5), and E(5,-4). What is the PDF of the distance between X and Y? Is it possible to find that with Maple? The similar question in three dimensions, replacing a square by a cube and a disk by a solid sphere.

solve Differential Equation : y"+4y=sin2x.

Recently I saw this question (http://www.mapleprimes.com/posts/141668-Partitions-Of-A-Natural-Number-Into-Factors). I want to find the divisors of a number, say 120, :

2,4,6,8,10,12,15,20,24,30,40,60,120

for the students but couldn't find a simple way for that expect the solutions in above link. Isn't an easier way to do this job in Maple?

Thanks so for the time

proc.mw

why doesn't this evaluate to a numerical value when u supply an a value for 'a'.

can someone modify it......

I've plotted the solution to a GLM using the plot3d function, but a portion of the plot is irrelevant to the presentation of the results. I can define the portion of the plot I want to discard based on the x and y coordinates, but I've gotten errors for every if-then statement I've tried to include. Any suggestions on how to properly integrate an if-then statement into the syntax?

Aslam-u-Alikum... How are you? Hope you will be fine. I want to determine the eigenvalues of differential equation in Maple kindly help me... Problem.docx

restart; 

g := proc (i) 
if i = 1 then a else 0 fi
end proc:

h := sum(g(i), i = 1 .. f);

The result is h:=0 instead of h:=a. What's wrong?

A number n is called a double if its base-7 digits form the base-10 number 2n. For example, 51 is 102 in base 7. What is the largest double?