cmcjas

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These are questions asked by cmcjas

Here is the question:Prior to this question I was given f(z)=z^2+1, N(z)=(z^2-1)/(2z), T(z)=z-I/z+I such that T(N^k (z))=(T(z))^2^k. And L is a set of number on the real axis. Now the question is that given we have two regions of the complext plane as follow:

R+ = {z : Nk{z) -> i as k -> ∞}; R- = {z : Nk(z) -> -i as k -> ∞}.

Draw a diagram to illustrate these regions, the line L and the roots i and -i. We call R+ the basin of attractionfor the root +i, and similarly R-is the basin of attraction for the root -i.

 Show that if z is on the set L (the common boundary of the two regions R+ and R_, then Nk(z) stays on L for all values of k. (This is easy once you identify what L is.) So in this case iteration does not produce a root at all.

So basically my problem is that the fact I'm not very familar with the commands to draw such diagram, and I don't know much about Newton's method to compute complex roots. It would be appreciated if anyone can help me how to get start with the question. Thanks.

 

First I know that the Newton-Raphson formula gives N(z)=z-(f(z))/(f'(z)). If f(z)=z^+1, then N(z)=(z^2-1)/2z

 

Then the Question asks me to first define two important functions which I did:

1)T(z)=z-i/z+i where is i is imaginery number, 2)N(z)=z^2-1/2z. Hence, I wrote the following in maple:

>T:=z->(z-i)/(z+i)

>N:=z->(z^2-1)/(2z)

Then I was asked to show that T(N(z))=(T(z))^2, so I wrote the following commands:

>z:=2

>T(N(z))-(T(z))^2 (I got zero for their difference, so they are equal)

next, the question said the same wave verify that T(N^2(z))=(T(z))^4, so i wrote:

>T(N^2(z))-(T(z))^4 (but I got 0.3239121662-1.392199407I which is a complex number, not zero but WHY?)

and the rest of the questions are as follow:

1) What will be the general result? <-I don't what does it mean by general result :S

2) T(N^k(z)) will be what power of T(z)? <-Is it power of 2k?I have no ideas.

3) Try T(N^3(z)).<-which I know that T(N^3(z))=T(N^2(N(z))), so does T(N^2(N(z)))=(T(z))^6 then?

 

It would be appreciated If anyone could help me with this/clear up my confusion with questions. thanks.

 

 

 

the question is as follow:

The partition does not always have to be equal intervals. Consider evaluating f(x)=x3 between 3 and 5, but splitting up the interval into a partition in which the end points of the subintervals are in a geometric progression. The common ratio r has to be chosen so that 3 is the first term and 5 is the last. Also the subintervals must be capable of getting smaller as n the number of subintervals increases. Check that the geometric series

a, ar, ar2, ar3,.....ari, .....arn =b

with r=  and suitable choices for a and b satisfies these criteria. Treating the difference between ari and ar(i-1) as the width of the subinterval and using the right hand endpoint of the subinterval, evaluate the Riemann sum to n terms for f(x)=x3. Find the limit as n tends to infinity to show that the partition does not affect the result.

here is what i have got so far, can anyone check if im doing it right? thanks

>a:=3:

>b:=a*r^10:

>r:=(5/3)^1/10:

>for i from 0 to 5 do a*r^i end do; -> a list of number appear in sequence ie:3, 3.157...,3.323...3.497...etc

>restart;

>a:=3:

>b:=a*r^100:

>r:=(5/3)^1/100:

>dxj:=a*r^i-a*r^i-1

>xj:=i*dxj+a

>f:=x->x^3

>evalf(sum(f(xj^*)dxj,i=1..100)) -> my value is sth like 162.4788870...

I tried to find the limit, but maple 16 freezed so i think i must have done sth seriously wrong?

<math xmlns='http://www.w3.org/1998/Math/MathML'><mrow><mi>b</mi><mo>&coloneq;</mo><mi>a</mi><mo>&sdot;</mo><msup><mi>r</mi><mrow><mn>10</mn></mrow></msup><mo>&#x3b;</mo><mo>&nbsp;</mo></mrow></math>

the question is as follow:

1)receive two integers p and q

2)declare two local p1 and q1 and give them intial values and q

3)check if p o q are equal or less to zero print works only with positive integers

4)while p1 not equal to q1 then p1-a1 otherwise q1-p1

5)whenever p1=q1 we have the GCD

note:must use procedure and call it for different values of p and q after the procedure is written

-by following the instruction above this is what i got

GCD:=proc(p,q)

local p1,q1;

p1:=p;

q1:=q;

if p<=0 OR Q<=0 then 'works only with positive integers'
else while p1<>q1 do if q1<p1 then p1-q1 else q1-p1

end if;

end do;

end if;

end proc;

but when I call two integers eg:p=2, q=6 -> GCD(2,6) maple just freeze...evaluating....forever. is it because i got the procedure wrong etc? it would be helpful if anyone can help me with this. thanks

 

 

Here is the question:

Consider f(x)=x3 over [a,b] and a partition P of [a,b] into n equal subintervals. Find the length of this subinterval and assign it to dxj.

a) Assign the rightmost point of the jth subinterval to xj. Set up an expression corresponding to the Riemann sum for this partition with  as the rightmost point xj in each subinterval.

b) Find the limit of this expression as n->∞. Integrate f(x) between a and b and comment on your evaluation of the integral and the value of the limit.

 d) Show that the limit of the Riemann sum remain unchanged if

xj = the left most point in the jth interval

or if

xj = the midpoint in the jth interval

 

anyone know how to go about this question? thanks

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