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visits member for 1 year, 10 months
seen Dec 2 at 22:55

Nov
25
awarded  Popular Question
Nov
18
awarded  Tumbleweed
Nov
13
answered Finding family of functions for which $\Delta h = 0$
Nov
11
asked How to generalize trace and determinant
Oct
12
comment What is the metric on a cone?
Much obliged! Thanks. Actually, the zero curvature is one of the reasons I picked the cone. I figure if I can go through all the machinations and get to zero, which I knew to be the case ahead of time, then I figure I am doing things right. It all seems to be working out, BTW. Thanks again.
Oct
12
accepted What is the metric on a cone?
Oct
12
asked What is the metric on a cone?
Sep
19
answered How can I calculate a polynomial trend line where `y` always increases as `x` increases?
Sep
18
comment Limit of a function containing square root.
It's someone's creation, maybe someone with authority, but still someone. They created a particular problem for you to solve. It involves $|\sin x|$ simply because the square root sign means "take the positive root". Sure, you can create another problem that would give results as in your second graph, but that's not the problem you are asked to solve. In answer to your question, "But why can't we define ... ?", well, sure, you can. But that's not what the author of the problem did. It's all a matter of meaning: The sqrt symbol means take the positive root.
Sep
18
comment Limit of a function containing square root.
"But why can't we define the function as positive for all the values in the domain?" We can do that, sure. But that is not what the author of your text book has done. The square root symbol simply has the meaning of taking the positive root. It's not that what you want can't be done. It's just that if you do that, you are solving a different problem than the one stated.
Sep
8
answered What does “*the best approximation $A_{a}(x)$ of a function $f(x)$*” mean?
Sep
5
answered Related rates of change - ship question
Sep
5
comment Related rates of change - ship question
You need to drop the constants from your equations for the rates. The constants don't contribute to the rate.
Sep
5
comment Equivalence of $P\rightarrow Q$ and $\lnot P\lor Q$
Think about what it takes to make $P\rightarrow Q$ false. Then take the "not" of that to make $P\rightarrow Q$ true.
Aug
31
comment Trying to understand “derivative or Jacobian of smooth map”
@Asaf Karagila I now understand that "jacobian" isn't an "official" topic tag. But wouldn't it be a good one to have?
Aug
31
comment Trying to understand “derivative or Jacobian of smooth map”
I wrote incorrectly in my question. I should have said a derivative looks to me like a map from R^m to R^(mxn), kind of like a gradient of z(x,y) is a map from R^2 to R^(2x1). Or that's the way I was looking at it. Thanks for your answer.
Aug
31
comment Trying to understand “derivative or Jacobian of smooth map”
OK, so as I understand it, my problems have involved notation and nomenclature. I was expecting the writer to say that the derivative was actually the matrix you have in your answer. To my mind, that matrix represents a mapping from R^m to R^(mxn). (I wrote that wrongly in my question. Oh well.) That is, to my mind, the matrix is the result of a mapping. But he is saying the matrix is a map (or a representation of ...). And the "inputs" to the map are the X's, not to be confused with the x's. The X's being sort "delta x's". How's that?
Aug
31
asked Trying to understand “derivative or Jacobian of smooth map”
Aug
29
accepted Looking for proof that $SO(3)$ is a submanifold of $\mathbb R^3$
Aug
26
comment A bag contains 4 balls. Two balls are drawn at random and are found to be white. What is the probability that all balls are white.
I'm just echoing what has been said but still, the problem as it is stated just doesn't give enough information to calculate a probability at all.