Recent content by gammamcc

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    Graduate Double integral showing a range of values?

    uuuhhh, is that a typo? I just took your approach as correct. Yikes! Anyway x^2 \geq \sin^2x, etc. Sorry to previous poster...
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    Graduate Physical definition of a complex angle

    The best justification I have seen is the famous formula by Euler e^(ix)=cosx +isinx (can prove via complex Taylor series of LHS). Cos and sin terms justify the real and imaginary axes and associated plots of the unit circle in the complex plane just like in trig - the formula justifies the use...
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    High School What are Some Calculus-Based Project Ideas for a High School Coal Fair?

    How about Leontief economic models. Study interdependence of coal with other industries using matrices.
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    Undergrad System of differential equations (classification of 3x3 case)

    Books are GOOD
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    Undergrad Should I use 2D or 3D graphs for Implicit Functions?

    Maybe try 2d but in polar... Looks like cartesian coords needs y=function of x noting samples on http://www.mathgv.com/
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    Graduate How Do You Set Up Integrals in Polar Coordinates for Volume Calculation?

    Cone? r=3sin\theta Check that. r^2=3rsin\theta x^2+y^2=3y on x-y plane Care to guess it is a cylinder? [Complete the square] So where is my bonus? Even a raise? Forget tenure...
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    Graduate Branch-cut singularity of a complex logarithm

    The problem with log z, is that the function is not single-valued if you allow paths which wind around the complex origin. If you approach a branch cut from different paths, you may get different limits. Towards a simple pole you get no limits at all. How they compare singularities may depend...
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    Graduate Can the 'Almost Reimann Integral' be Recovered Using Pinsky's Textbook?

    Try the textbook by Pinsky: Partial Differential Equations and Boundary-Value Problems
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    Graduate How can we determine if a closed symmetric operator has self-adjoint extensions?

    I only know of a VN thm involving one-parameter unitary groups of operators. Your problem looks as if you have to prove closure and to look at the associated resolvent operator.
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    Undergrad How to minimize a simple quadratic function of multiple variables ?

    I wouldn't expect a simple answer. I would liken this to linear regression; cf. http://en.wikipedia.org/wiki/Linear_regression
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    Undergrad Understanding Derivatives: Real-World Application Examples

    Derivative is the rate of change over an instant of time (hence it's a limit). On the ladder problem, it would be like little speedometers on the corners of the ladder. If you graphed height of latter vs. time, say, the speedometer at any time during the fall comes out the same as the slope of...
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    Graduate Minimising the action for surface area in AdS

    Well, it seems the integral may very well be zero with the right choice of U' and U over an interval of positive r. Considering the even powers involved, there are not many choices other than U= (?) ans: U=0 (identically).
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    Graduate 2nd order nonlinear non-seperable equation

    dy/dx time y comes out dy/dx times dx/dy = second derivative of x w.r.t t ? Anyway, I see some constant solutions... Check and see. Any initial conditions on the problem?
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    Graduate Minimising the action for surface area in AdS

    I see integral w.r.t. tau and U is a function of what? r? BTW: What is the interval of integration?
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    Graduate Minimising the action for surface area in AdS

    I see integral w.r.t. tau and U is a function of what? r?