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1. Finite Fourier Transform on a 3d wave

Finite Fourier Transform on a 2d wave How does the finite fourier transform work exactly? The transform of f(x) is \widetilde{f}(\lambda_{n}) =\int^{L}_{0} f(x) X_{n} dx If I had a 3d wave equation pde and I applied Finite fourier transform on the pde for z(x,y,t)=X(x)Y(y)T(t)...
2. Proof using f(x1,y1)-f(x0,y0)=fx(x*,y*)(x1-x0)+fy(x*,y*)(y1-y0)

1. Homework Statement [/prove f(x1,y1)-f(x0,y0)=fx(x*,y*)(x1-x0)+fy(x*,y*)(y1-y0) prove there exists a point (x*,y*) if fx and fy are all continuous on a circular region and contain A(x0,y0) and B(x1,y1) 2. Homework Equations [b]3. The Attempt at a Solution I'm thinking mean value...
3. How do you tell what a vector space will look like from it's spanning set.

I'm having a hard time visualising them. How do you plot vector fields How do you plot spanning sets? How do you tell if something spans a plane, 3d, a line or more dimensions.
4. Basic basic javascript form validation. literally need an help

Javascript is in an external file liked by this: <script type="text/javascript" src="myscript.js"></script> in the head tag i have <form name="myform" action="" method="POST" onSumbit="return validateForms()"> and some form stuff and then: <input type="submit" value="Submit"...
5. Implicit partial differential for unknown function F(x,y,z)=0

1. Homework Statement F(x,y,z)=0 x=a(y,z) y=b(x,z) z=c(x,y) what does \frac{\partial c}{\partial x} \frac{\partial b}{\partial z} \frac{\partial a}{\partial y} equal. 2. Homework Equations maybe you could tell me? 3. The Attempt at a Solution i've spent hours and hours...
6. What does 2nd ord pde tell you? like fxx(x,y)

pure and mixed, what do they tell you about a function?
7. Wht does this sign mean?

(\frac{\partial z}{\partial x})y the small y, what does it mean. the context this is used in is F(x,y,z) where each variable is a function of the other 2 variables.
8. Volume under curve z=1-x^2-2y^2

1. Homework Statement z=1-x^2-2y^2 find volume under curve bounded by the xy plane. is the answer sheet wrong? (see below) why am i struggling so much with this??!?!?! how do i do it? 2. Homework Equations according to other answer sheet, it is pi/sqrt 2 3. The Attempt at a...
9. Vector space prove 0u=0

1. Homework Statement prove 0u=0 where u is in the vector space. 2. Homework Equations the 10 various axioms for addition and scalar multiplication. 3. The Attempt at a Solution pretty much just (u+-u)u=0 or (1-1)u=0 1u+-1u=0 and then i get stuck. i can prove that...
10. Show its not a group for # where a#b=a+b-ab in the set of all real numbers

1. Homework Statement In set theory, i have a two part question, the first is showing that the system S={set of all real numbers( \Re )}, #} where a#b=a+b-ab we have to show that it's not a group. and then find what c is so that the system = { \Re \cap\overline{c}, # } is a group. 2. Homework...
11. 3-10 points why you believe in the theory of evolution and big bang

Can you give me 3-10 points why you believe in the theory of evolution and/or the big bang? this is independant of any other theories. I'd like it numbered. and just brief points, like a topic and brief explanation of why this makes you believe evolution and/or the big bang to be true. I'll...
12. What is 3 digit arithmetic?

what is 3(or i, where i=1,2,3,4......∞) digit arithmetic? is it just working with 3 decimals or 3 significant figures? or is it base 3 arithmetic?
13. RFID attendance marking, what infrastructure?

RFID attendance marking, what infrastructure?? im trying to plan for an RFID system. 1)what resources and material and general infrastructure do i need? 2) i think i want it to connect it up to my Uni's intranet maybe wireless, so i'd only need to wire the power source? this good? 3)...
14. MATLAB Basic matlab q on writing error messages

How do you write error messages for when a function has been given an input that is illogical for what the function does. in matlab function b = bla(a) for example if a < 0 i want it to display a message
15. Conditional Probability

1. Homework Statement romeo proposed to juliet. now hes waiting for her response. R = 'event that she replies' W='event that she wants to get married' Mon = 'event on monday' Tue = 'event on Tuesday' P(R\wedgeMon | W) = 0.2 P(R\wedgeTue | W) = 0.25 P(R\wedgeMon| \bar{W}) = 0.05...
16. MATLAB Matlab and floating point, function for min n max?

so i found this program matlab on the computers at uni. ive been messing around with it. right now im learning a bit about floating point systems and stuff and i thought it would be cool to write up a function that finds the smallest and largest numbers but turns out its harder than i first...
17. Questions and answers for a test covering a variety of things?

im trying to study but i have um misplaced my textbook. (it ran away from me, after i neglected it whilst doing other assesments) so i would greatly appreciate just a couple questions with answers, (feel free to give me more though ;) ) on any of these things (in order of priority) -...
18. Check my working for finding if vectors are parallel ?

1. Homework Statement there is a line through A : (1;-2; 1) and B : (0; 2; 3) and the line through C : (4; 1;-2) and D : (2; 2; 2) are they parallel? 3. The Attempt at a Solution i said no they weren't. i had the lines as being: (-t+1)i+(4t+2)j+(2t+1)k and (-2t+4)i+(t+1)j+(4t-2)k...
19. When integrating by trig substitution why do you use what you use?

when integrating by trig substitution why do you use what you use?? for example int. (1+x^2)^0.5 dx why do you use x= tan u i mean obviously because it works, but if you didn't know it works how would you figure it out? i would think that you should use x=sinh u but ive been trying...
20. Some questions for non/homogeneous equations

what do you do when m=0, do you just have 1 term + a constant? what do you do when there is only 1 value for m. do you have Ae^mt + Ate^mt or what? im a little confused. EDIT -for differential equations i mean, when youre trying to solve for y and the equation has differentials of y in...
21. Is there any point in buying cloud services locally or internationally or what?

pros and cons if any?
22. Is it mathematically sound to do this

apply integration by parts twice and swapping the u and v's and then rearranging the equation to say that it is equal to bla/2 like for example i said u is x^n or something and v' is sin x or something. later on when im faced with another integral, i apply the int by parts but this time...
23. Laplace of non-homogeneous

1. Homework Statement do a laplace transform on a given non homogeneous equation. to eventually find out y 2. Homework Equations i dont think the equation is needed. however this non homogeneous equation is equal to Ae^kt 3. The Attempt at a Solution well. i applied the laplace...
24. On a scale of 1-100 how bad is my graphics card?

1 being the worst you can buy right now, 100 the best you can buy right now i got a mobile intel R 4 series express chipset family with a booster: nvidia geforce G210M cuda 512Mb i think thats right. >.> could be wrong though :s the dxdiag window thing just says the mobile intel r 4 stuff but...
25. Can someone explain Laplace transformations

Can someone explain Laplace transformations!!!!!!!!! i dont understand ittttt.  sorry. i hadnt even heard of laplace transformations until i found it in my assignment. basically i want to know how to use them so, some simple, well explained examples perhaps?
26. General solution of integration by parts of int(x^n*e^x)

1. Homework Statement i have to create a general formula for integral of (x^n * e^x) dx using whatever method i deem appropriate. (the only way i could think of is by parts) 2. Homework Equations int(x^n * e^x)dx int(uv')dx=uv-int(vu')dx 3. The Attempt at a Solution i used...
27. When does a limit not exist.

I cant remember exactly. I'm thinking its when its not continuous or differentiable. but is there more exact definitions/am i wrong/anything really.
28. I^2 = -1 or +1

i was taught that i2 = -1 because ((-1)1/2)2=(-1)2/2=(-1)1=-1 but isnt it mathematically correct to say \sqrt{-1} * \sqrt{-1} = \sqrt{-1*-1} = \sqrt{1} = 1 what the heck!! Is there some bleedingly obvious thing im missing.
29. Reverse product rule?

1. Homework Statement i'm sorry i know i've been bombarding physics forums with questions but i need help :p using reverse product rule \int uv' = uv - \int vu' and say i have a*b i noticed my teaher said that a=u and b=v not v' and he simly made that into a v' by deriving. is there a...
30. Exponential Integral

1. Homework Statement i have to integrate e^(-y) / y and i found out that you have to use this exponential integral and someone else said it doesnt have an integral. either way im thoroughly confused 3. The Attempt at a Solution i have no clue what so ever. The original question had it...