s243a
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Everything posted by s243a
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http://graham.main.nc.us/~bhammel/graham/C.htmlI agree that c++ has more features and in that since it is better however you can program in an object oriented style in c. True it doesnt have classes but it has something called type definition and structures. You can implement methods by having fields in your structure that are pointers to void. You can implement subclasses by renaming an exciting type with a second type. Then you can override methods by changing the pointers. If you want to include new fields in the subclass then make sure there is a field in the original type called children. If you want to do multiple inheritance in c, which is legal in c++ but not java than the child would have to point to the parent instead of the parent pointing to the child. This will make polymorphism more difficult to handle. Anyway, anything that is legal in c is legal in c++ so it is not really hard to switch from c to c++. So why not switch? Arent more features better? Well it depends, not all processors have c++ compilers, c is a much smaller language, it is much easier to see what is going in at a low level with c then c++ because the translation from c to assembly is almost just a straight look up. Some programming environments that interface with hardware (ex. Lab windows) supports c and not c++. So if you know c you can use you code in more places but if you know c++ while your code will probably be easier to read. Take your pick. From:http://graham.main.nc.us/~bhammel/graham/C.html
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Hmmmm?..Skate boarding. It is been a while (9 years maybe?). I have roller bladed and skied much more recently. Kick flip yeah I could do triple kick flips sometimes. I forget what an olli 50-50 was. I use to be able to do 180?s maybe 360?s in the air when olling, lots of grinds, olli down stairs. I never did more the four or five stairs. I never had too big a bail on a skate board. I was roller balding down a hill this year and tried to turn to quickly into a drive way. I had road rash over half my stomach. The worst I would get for skateboarding is a scrapped elbow or a mildly sprained ankle. I use to hate when I land a trick on my heal. I never figured out how pressure flips worked. I could do an Olli impossible though.
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I never used matrices for boolean algebra or discrete structures but it sounds interesting. I havnt taken a discrete structures course but I have taken a discrete math course (close enough). I agree that expressing things in matrices can greatly simplify some expressions. For instance simpler is simpler y=Ax or y1=a11 x1 + a12 x2 y2=a21 x1 + a22 x2 I have seen it mentioned in a first year linear algebra course,( I think in the context of linear transformations) but it is more something for a second or third course in linear algebra. I my self have only taken one course in linear algebra but I have seen bits and peaces of matrix algebra in other courses. I learned about tensors because I was interested in relativity. Maybe I picked it up on a news group or something. Unfortunately I never was able to fit relativity into my schedule. I forget which courses I chose instead even if I could fit it in. When I was at Mount Allison University doing physics it was taught by Dr Hawks. He was a really good teacher and the course would have been exceptional. Oh well hopefully some day I will learn it on my own. On book I read mentioned that many material properties can be expressed in terms as a tensor. For instance strain and modules of elasticity. I am surprised you have leaned about Hermatian matrices. The only place I have used those is in quantum mechanics courses. Maybe they might also be used in electromagnetism somewhere. I think one good course in linear algebra can get you quite far. I suspect it gets pretty abstract once you get to the third course. I have only taken one course on linear algebra anyway. Some interesting matrix concepts you might be interested in are: Positive definite matrices Positive semi definite matrices Singular value decomposition Pseudo inverse Orthonormal matrices
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I mean the sum over all elements after you did element wise multiplication. Recall for matrices/(row vectors) [a b] and [c d] element wise multiplication is done by multiplying corresponding elements to obtain a matrix of the same size. Thus: [a b] .* [c d]=[(ab) (cd)] Gives a two by two matrix with the first element equal to (ab) and the second element equal to (cd). Notice the dot product is: [a b] dot [c d]=(ab)+(cd) Thus you can think of the inner product/(the dot product) as element wise multiplication followed by a sum. It is not really necessary to think of the intermediate step. However the programming environment MATLAB allows you to do element wise multiplication by using the sybol .*. Incidentally it also uses semi colon for a new row and space or comma for a new column. Thus I am also teaching a bit of MATLAB without you even knowing it. So the answer you are looking for is 23 and not 14. Also in linear algebra books they say mathematicians did not define matrix multiplication element wise because they instead formulated a more useful definition. Although true element wise multiplication is very useful for programming and it does make certain mathematical expressions easier to express. I think that linear algebra books shouldnt so easily dismiss it as a useless idea. If I get around to showing you how to write a program that will do a generalized multiplication of arbitrary dimensions you will see how I will use element wise multiplication to define normal matrix multiplication.
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I really dont care anymore about the post count. I am sure I am well above the number of posts I need for the introductory package which I am sure is a lot more then I need anyway. I also found an alternative place where I can upload files with a .wmz extension. When I get time I will get around to requesting the package again just so I can compare and see which web service I like better. I am enjoying the conversations here. P.S. why cant you give someone a plus and minus on the same day?
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I am not double posting I am adding to the discussion. Why should I post everything on the same post. That would lead to incredibly long posts that no one would want to read. I personally would rather if people have a new thought to add to a discussion for them to put it in a new post that way I could see if anything has been added to the topics I am interested by checking the new messages. If you really hate to see people constantly adding new stuff to a thread when you check the new messages maybe the message board should be upgraded so people can filter out topics they are not interested in when they check the new messages
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I agree with you on both points but that is not really the point.
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I said no engineering work experience. I worked for public works, I?ve worked in factories, I?ve tree planted, blueberries racked, picked strawberries. I have tutored marked assignments and now I am writing some code for mechatronics labs. Anyway to suggest that I won?t need to know any high level math as an engineer is a little ludicrous. If that wasn?t what you were suggesting why bring it up.
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Hmmm?.This thread is not taking off yet. I?ll start? Has anyone ever done threading before? I have done a little bit in Java for two of my school courses but it was two or three years ago so I forgot most of it. I didn?t like the Java threading model because there was no concept of priority, no rules for which orders the threads get executed in and their was no built in way to interrupt the threads. That is not to say you couldn?t interrupt the threads if you new some obscure system commands. Of course you don?t need to use the built-in threading libraries of a language. You can use an external library. The two I might learn are windows 32 threads and p threads. Anyone else have any thoughts, stories etc, on threading?
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And to this I rhetorically and fictitiously respond why go to school at all after grade six? Heck why not send kids to trade school after grade six and the ones that don?t want to go to trade school send them to the factories. Take this with a little bit of sarcasm.
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Well you can get by without knowing a lot of stuff in everyday life. So if you are going to use that attitude why do we need anything above grade six. What we dont know about language spell check and grammar check will teach us on word right? When I was younger I didnt like French. I wish I new it now in case I every wanted to work in Quebec. Anyway math is similar to language. The ideas we can have are formulate in math, languages, images or sound. If you limit your self in math you limit the amount of thoughts you can express. More importantly math strengths our problem solving and reasoning skills. You are right that computers do a lot of calculations today. They can even prove theorems for us now. However it is very helpful for the people using these programs to understand what is going on. Moreover many ideas in physics are expressed in mathematics. Some ideas are very difficult to express linguistically and with out understanding the mathematics you comprehension of those ideas becomes limited. The more math you know the faster and easier learning science, engineering, economics, business, computer programming and becomes. It is my opinion that learning mathematics greatly enhances our ability to learn new concepts. Anyway if you dont like it no one is forcing you to learn it.
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I think finding the angles of a right angle triangle is usually thought somewhere between grades six and 9. I think I leaned it in grade 7. If it was up to me I am not sure when I would teach it.
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I have edit and I didn't plan on double posting. Yeah thats right that is the most basic trigonometry (right angle triangle stuff)Oranges have skins (O/H=sin(theta)) Apples have cores (A/H=cos(theta)) Oranges are tasty (O/A=tan(theta)) Theta denotes the angle O denotes the opposite side H denotes the hypotenuse A denotes the adjacent side For non right angle triangles see the law of sines and the law of cosines.
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Okay, here is a mail delivery program. You are delivering mail to N cities by air. Given an initial take off point find the shortest flight route to travel to all N cities. Determine the computational complexity of your program.
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Thinking back to when I first leaned about sine and cosine I remember it is a way to get the angle in a right angle triangle. Sine and cosine are periodic functions. Many angles can be derived analytically using the unit circle and trigonometric identities. Others must be derived numerically. One way to do this is a series expansion of the trigonometric functions. For instance a Taylor series. To fully understand Taylor series requires a knowledge of calculus. Hmmmm.Locking back maybe I should find another site that I can link concepts to wolframs mathworld has just about everything but some times I think a simpler explanation might be better for some people.
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We all have are things we are good at and not good at. We become good at things mostly by hard work but natural ability also helps. If you are only thirteen and already know what sine and cosine are, you are probably ahead of most kids your age. I have been in university for eight years. Each year of university you learn a lot more then in high school and your level increases substantially. I am impressed to even see a thirteen year old try to read what I posted. I purposely made the post really dense with concepts so anyone who was up to the challenge of learning it would learn a lot really quickly. We improve the fastest when we are challenged just enough to push are limits but not enough to exceed them. I feel my greatest gains in conceptual ability come when I feel like I have to beat my head against the desk to figure out the problem or understand something. A good challenge can make the smartest person feel dumb but when they succeed they should remember what they conquered.BTW there seems to be a lot of young people here. I am 26.P.S. If you want to lean about a particular math concept feel free to ask.If you lean this stuff at 13 you will be so far ahead of people it won?t be funny.
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I think the idea is to share my idea of generalizing matrix multiplication and to get some feedback back. I would like to know are my ideas sound. I would also be interested in learning more about tensors. I may read the link I posted about tensors to help me learn more. I would be interested in how my ideas of generalized matrix multiplication fit into the ideas of tensors. Anyway I just wanted to start some discussion about mathematics here. Someone may bring up another topic and the thread my diverge. Isn?t part of discussion gropus about sharing ideas and learning for each other. For instance in the http://newmars.com/forums/ group I frequently post to, it is not unordinary for someone to propose an idea for space propulsion. The members may then respond by saying how reasonable or unreasonable the idea is and how it fits into present ideas about propulsion. I think sharing information and leaning form each other is an important part of discussion groups. So basically I started off by just sharing some of my currents thoughts on math. Has anyone here been thinking about any mathematical concepts lately?
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I am a student studding my masters In electrical engineering (control systems). My thesis is about identifying non linear parameters of a motor using a quasi linear kalman filter. I have two undergraduate degrees, one in physics (math minor) and one in electrical engineering. I would enjoy teaching if I had good students but as far as bellow a university level there is not the same potential to make money. I have yet no engineering work experience but hopefully some day I will find a good job. If I didn?t need a bachelors in education to teach math to high school I could consider it for a bit. However that is not the way the system works. I tried tutoring for a bit. I really enjoyed that. If I had spare time in the future I could consider that as a hobby.
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Pardon me? I spent considerable time writing this. I am not affiliated with any of the sights I linked with hyperlinks. The links were chosen to provide the reader with further information beyond what I have written to help fill in the gaps. Is a discussion of high level math or science forbidden here? Must I always talk to the lowest conman denominator? I tried to proved explanations to my original post because people asked questions about it. Otherwise I could just talk completely over most peoples heads and hope someone with a similar interest joins in. As far as formatting and such I spent a lot of my time trying to make this post as neat as possible. If there was an alternate text attribute to the image take I could try to replace some of the text by pictures to make it neater. However that would mean my document would not be self contained and if any servers went down the post would make no sense at all. If you could guarantee me web space than I would have a safe place to store my images. However I know the nature here is not to guarantee people web space but rather regiment them to post in a regular pattern following a possibly ridged set of guidelines. BTW what is the preoccupation here with calling everything spam. Isnt span just chain mail and unwanted advertising. This certainly isnt chain mail and what the heck do you think I am advertising????????
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To make this more interesting to people who are just taking geometry here is an example of how matrix multiplication can be used for analytic geometry applications. We can represent a point on a plane as so much to the right, say a to the right and so much to the left, say b to the left of a point called the orgin. The orgin could be the bottom left corner of the paper. Thus the other point is: [a] You can preforme many transformations on this vector for instance you can rotate the point it represents about the orgin by left multiplying the vector by the following rotation matrix [cos(theta) sin(theta)] [-sin(theta) cos(theta)] That is if [c; d] is the point after rotation then: [c] [cos(theta) sin(theta)][a] [d]=[-sin(theta) cos(theta)] The matrix: [cos(theta) sin(theta)] [-sin(theta) cos(theta)] Peformes a linear transformation on the vector [a; b]
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Okay, well lets start with the basics. The inner product also known of as the dot product is the sum of element wise multiplication. For instance if you have two vectors [a b] and [c d] then the inner product is ac+bd and is denoted: [a b] dot [c d]=ac+bd The operation is done by first doing element wise multiplication which I will denote as .* for example: [a b].*[c d]=[(a*B) (c*d)] And then by taking the sum of the resulting vector. Sum_{over all elements}=(a*B)+(c*d) The inner product is a measure of how close two vectors are, some applications include geometry and signal processing. Matrix multiplication can be thought of as row by column multiplication. For instance. Let: A=[a11 a12][br] [ a21 a22][/br]and B=[b11 b12][/br] [b21 b22]If C is the Matrix product of A and B then: C=[([a11; a12] dot [b11; b21]) ([a11; a12] dot [b12; b22])][br] [([a21; a22] dot [b11; b21]) ([a21; a22] dot [b12; b22])] Notice that an inner product of the rows of A are formed with the columns of B. The outer product is the opposite of the inner product in the since that the size of the resulting matrix increases instead of decreases. For instance the outer product of the vector [a b] with [c d] is [ac ad][/br] [bc bd] Note that ac denotes a*c Now lets distinguish between a row and a column vector. A row vector will be a horizontal vecor For instance [a b] And a column vector will be a verticale vector: [c][br][d]We will use a semi column to denote a new row so [c; d] will also be considered a column vector and [ac ad; bc bd] will be considered a 2 by 2 matrix. In matrix multiplication the inner product of two vectors is: [a; b][c d] or [c; d][a b] And the outer product is: [a b][c; d] or [c d][a; b] This is a result of how matrix multiplication is formed by the row by column multiplication.
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I think their is a word count or something. I think it takes many little posts to count as one post. Anyway this section is venting so their should be some freedom in content right?
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Well if it is too much work I would look for alternatives. Angel towns said they added wmz files to my my allowed file list. Unfortunately I still can?t upload them. Anyway I posted some more thoughtful stuff in the computer section under languages. Atleas a little more thoughtful but know one responded yet. I am more interested in a science/mathatics/space form. Maybe there are other people here that are interested in this stuff. Time will tell. My favorite discussion group is http://newmars.com/forums/. My favorite newsgroup is sci.math, sci.math.symbolic, and the matlab news group (What was that called.) Anyway I look forward for a positive experience her but I have been trying to find suitable webspace since 2:30 it is now 10:13. Things aren?t going well yet.
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Hmmm... Angel file responded to my email and added the file type I was looking for. If trap doesn't accept me atleas I have another alternative. I will check back tommorow.
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Tekken Force is too hard. I want Dr. B and I was only able too beat Tekken Force once not the required 3+ time. I am too busy to get good enough to beat Tekken Force.