Recent content by Svein

  1. Svein

    I Problem in understanding instantaneous velocity

    Copyied from "Real Analysis" (H.L. Royden): These are topological spaces. T_{1}: Given two distinct points x and y, there is an open set which contains y but not x. T_{2}: Given two distinct points x and y, there are disjoint open sets O_{1} and O_{2} such that x\in O_{1} and y\in O_{2}. T_{3}...
  2. Svein

    I Convergence not defined by any metric

    Copyied from "Real Analysis" (H.L. Royden): These are topological spaces. T_{1}: Given two distinct points x and y, there is an open set which contains y but not x. T_{2}: Given two distinct points x and y, there are disjoint open sets O_{1} and O_{2} such that x\in O_{1} and y\in O_{2}...
  3. Svein

    I Convergence not defined by any metric

    I seem to remember that metric is a strong topological property. For weaker topologies continuity is defined as that the inverse funcion of open sets are open. Whether this is applicable in this case I cannot say on the top of my head.
  4. Svein

    I Do non-orthogonal coordinate systems mean dependent coordinates?

    What is "orthogonality"? You need to add some structure to your space in order to define it. The usual version is a Hilbert space, where you define a "scalar product" of two vectors. If that scalar product is 0, the vectors are said to be ortogonal.
  5. Svein

    Is AI hype?

    If you disconnect from the Internet, can the so-called "AI" apps ace the Turing test? In 1955 the Eliza program was nearly there (no Internet then).
  6. Svein

    B Which conditions should I check to see if a quadrilateral is a square?

    4 sides equal and both diagonals are equal.
  7. Svein

    B Confused about ciphers in the book 'Arithmetic for the Practical Man'

    A "cypher" is another term for something that is converted from a readable format to something that is not readable. The reader then needs a "key" to convert the coded text into readable format.
  8. Svein

    I A curve that does not meet rational points

    I think the relevant answer is the "bump function".
  9. Svein

    Resistor Color Code

    Ah - colur codes. I remember way bak when TV could be repaired and often had to. A common fault in a certain model was that the cathode resistor had a tendency to burn out. The standard replacement resistor was 1kohm (brown - black- red). One low-level repair guy was red-green color blind...
  10. Svein

    B Is Each Stage of Pascal's Triangle Special?

    Also observe that 2^{n} = (1+1)^{n}=\sum_{i=0}^{n}\begin{pmatrix} n \\ i\\ \end{pmatrix} 1^{n-i}\cdot 1^{i}=\sum_{i=0}^{n}\begin{pmatrix} n \\ i\\ \end{pmatrix}
  11. Svein

    B Is Each Stage of Pascal's Triangle Special?

    Look at the triangle. Observe that each element is the sum of the two elements above it (in your row, 6=1+5, 15=5+10, 20=10+10 etc.).
  12. Svein

    B Are Implication and Equivalence Interchangeable in Logic?

    In predicate calculus A\Rightarrow B is defined as \neg (A \wedge \neg B) , or (using deMorgan) \neg A \vee B . Expressed in words: You cannot have A and not B, or the converse: If A is false, B can be anything.
  13. Svein

    Why do emails from my contact form bounce?

    Have you tried "ping example.com"? You may not have the applicable DNS. Or does your program need to know how to access DNS?
  14. Svein

    B Why 186,282?

    As far as I remember the speed of light in vacuum is determined by the formula c= \frac{1}{\sqrt{\epsilon_{0}\cdot \mu_{0}}}. The actual numerical value follows from that. BTW the speed of light in any environment is given by c = \frac{1}{\sqrt{\epsilon \cdot \mu}} where ε is the dielectric...
  15. Svein

    C/C++ Parallel processing for loops and pointer defined outside the loop

    Thhis is the trouble with "objectified C". If you want to do this in C, you would put this code in a separate module and declare the pointer as "static" (which means that only code in that module can access it).
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