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revised Show that the area of a triangle is given by this determinant
the reasoning was not correct in the second step
Jul
28
revised Are convex functions enough to determine a measure?
deleted 5 characters in body
Jul
28
answered Convex sets in $\mathbb R^n$: Do they have a particular form ? Does the gradient of a linear convex function $f$ exist on such a set?
Jul
28
revised Are convex functions enough to determine a measure?
added 155 characters in body
Jul
27
answered Are convex functions enough to determine a measure?
Jul
24
answered inverse a function with exponential and first degree polynom
Jun
27
awarded  Enlightened
Jun
27
awarded  Nice Answer
Jun
10
comment Find minimum value of $|2z-1|+|3z-2|;\,\,z\in\mathbb{C}$?
$|z+w| \le |z| + |w|$ is the triangle inequality
Jun
10
answered Find minimum value of $|2z-1|+|3z-2|;\,\,z\in\mathbb{C}$?
Jun
10
answered Diffeomorphism of the sphere
Jun
10
answered How to solve $e^{ix}=i$?
Jun
4
answered What is the solution of cos(x)=x?
May
25
comment Rewrite trigonometric expression to be be numerically “stable”
Yes, I would prefer a formula which is exact and which is defined at x=0. But maybe such a formula does not exist...
May
25
comment Rewrite trigonometric expression to be be numerically “stable”
Yes, this is nice! However I need to apply this formula also for "non small" values of $x$. I think I could use $x/3$ when $|x| < 0.01$ and the exact formula elsewhere...
May
25
revised Rewrite trigonometric expression to be be numerically “stable”
added 134 characters in body
May
25
comment Rewrite trigonometric expression to be be numerically “stable”
Yes, I could use Taylor series, but I should distinguish the case when x is not small... that I would like to avoid.
May
25
asked Rewrite trigonometric expression to be be numerically “stable”
May
21
answered Can I prove Pythagoras' Theorem using that $\sin^2(\theta)+\cos^2(\theta)=1$?
May
18
revised Affine Independence $\iff$ Linearly Independent
deleted 1 character in body