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 Mar 10 answered Find the matrix given the determinant Mar 2 comment Integrating a step function using antiderivatives $F(x)$ is not continuous. It should be piece-wise continuous. Feb 27 answered How can one intuit complex numbers from quaternions? Feb 25 comment Transformations between coordinate frames Your transformations dont look right. In your notation $T_{AB}, is that from A to B or the other way around. Feb 23 comment Transformations between coordinate frames Luigi, they are Homogeneous coordinats. Feb 22 comment Derivative of angle between two vectors singularity! I think that you might be running into trouble with your assumption that A and B are unit vectors. By that assumption you cannot arbitrarily change one of the vectors. It has to remain on the unit circle. Thus$\bf \dot{\hat A}\dot \bf \hat B$and$\bf {\hat A}\dot \bf \dot{\hat B}$are both zero. So you have a situation where you have$0/0$and you would have to use L'Hopital's rule to solve it. I recommend that you solve for the general case. Feb 22 answered Solving a transformation equation involving vectors and quaternions Feb 22 comment Solving a transformation equation involving vectors and quaternions Because quaternions are not commutative, you cannot divide. You have to pre or post multiply to manipulate both sides of the equation. Feb 22 revised Confused with the notation/halfway done and need a little help put in$$Feb 16 comment Quick question about ln(0) You know about L'Hôpital's rule right? Just put the indeterminate form into$\infty/\infty$form as follows$x \ln x = \frac{\ln x}{1/x}$. Then take derivatives. It is pretty straight forward. Feb 16 comment Quick question about ln(0) You could also side step the indeterminate form by solving the equivalent integral down the$y$axis.$\int_{0}^{1}\ln x\,\mathrm dx=\int_{-\infty}^{0}e^y\,\mathrm dy = -1$Feb 8 comment compare lines and recognize similar ones I think that instead of convolution you meant correlation. Convolution reverses one signal in time which would not yield the desired result. Correlation on the other hand does not reverse time and therefore would be more applicable. Jan 31 revised How to check if a matrix is positive definite added 1 character in body Jan 5 reviewed Approve Show there is a path in X$\times$Y if and only if there is a path in X and a path in Y Jan 5 reviewed Approve Find least possible number of factors Dec 14 awarded Yearling Nov 21 comment Proof with Positive Symmetric Matrices Just work it out by the definition of SPD$x^TKx > 0, \forall x \in \mathbb R^n$. Nov 15 comment Matrix Differential Equation with a Skew-Symmetric Matrix Please provide an example Sep 11 comment Why does$x^{(1/\ln(x))} = e\$? Take the natural log of both sides and insight is not far off. Jun 12 comment Curve fitting to connect certain points What is the significance of the blue curve? Why are the interpolation points represented as triangles? How do they affect/constrain the black curve?