Recent content by lypaza

  1. L

    What are scalar multiples and projections in vector operations?

    So I have to find angle theta between v and L, and then find vector w with negative theta? I also have to find the plane of v and L by cross product of v and L ...
  2. L

    What are scalar multiples and projections in vector operations?

    [PLAIN]http://img62.imageshack.us/img62/5319/49966749.png What is the scalar multiples of a vector actually? I was thinking L = c[2 1 2]T Then I looked for projection of v on L. But I got c in my answers which are not supposed to be...
  3. L

    Basis and Dimension of matrices

    It said 24 is correct. So we were dealing with R5. This is R5x5. I guess the number elements on the main diagonal should be more than 20, but I only see 5 elements: a11, b22, c33, d44, e55 of 5x5 matrices A, B, C, D, E...
  4. L

    Basis and Dimension of matrices

    But when I submitted the answer, it said incorrect... http://img192.imageshack.us/img192/6831/49103767.png
  5. L

    Basis and Dimension of matrices

    4? So the dimension is 4?
  6. L

    Basis and Dimension of matrices

    you mean ax1 + bx2 + cx3 + dx4 + ex5 = 0 ? where a, b, c, d, e are elements on diagonal
  7. L

    Basis and Dimension of matrices

    Ok, I think this one is a little bit trickier If S is the subspace of R5x5 consisting of all matrices with trace 0, then what is dimension of S? I found out that trace is sum of the diagonal. And I also found out that symmetric matrices have zero trace. The problem is I don't know how to find...
  8. L

    Basis and Dimension of matrices

    Never mind. I think I found it :D Editing: Yes, it is 21 :D
  9. L

    Basis and Dimension of matrices

    If S is subspace of R6x6 consisting of all lower triangular matrices, what is the dimension of S? Does anyone know the properties about dimension of lower triangular matrices?
  10. L

    Solved: Proving x^4-3x^3+4x^2-3x+1 \geq 0 for all real x | Polynomial Inequality

    Think about (x - 1)^3 = x^3 - 3x^2 + 3X -1 When you have A(x).B(x) >= 0, and you know A(x) >= 0 for all x then you prove B(x) >= 0 for all real x.
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    Comp Sci Help with Counting Objects Created in a Java Class

    I have one more question about static variable. If I have an array: Student [] students = new Student [20]; and I have to write a method to create a Student object and put a reference to this student in the students array. For each time adding one student, I have to know how many students...
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    Comp Sci Help with Counting Objects Created in a Java Class

    Oh, my! I couldn't think in that way. If I don't have a default constructor methods, can I conbine like this? public class Student{ private String name; private int age; private double gpa; private char [] courseGrade; private static int count = 0; public Student(String name...
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    Comp Sci Help with Counting Objects Created in a Java Class

    public class Student{ private static int count = 0; public int getCount(Student s){ if (s == new Student()) count++; } } I don't think it would be correct :rolleyes: I feel I still miss something, do I need a loop to go through the class to get...
  14. L

    Comp Sci Help with Counting Objects Created in a Java Class

    I still don't get it. Can you give me some more clue?
  15. L

    Comp Sci Help with Counting Objects Created in a Java Class

    Oh yeah, today we were talking about static variables. But what signal would be to indicate the object is created? :confused:
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