Recent content by Bruno Tolentino

Yeah! Conceptually, I understand the short selling and I know how to calculate the gain or loss using a notional amount. But, I wouldn't like to use the notional amount because this requires refined calculations. I'm working an asset and I do backtests. I know that is possible to calculate the...

A stock, in the first year, cost 128 dollars; in the second, cost 64... D - Price 1 - 128 2 - 64 3 - 32 4 - 16 If I buy 100,000 dollars of this stock @ 128 dollars / share, so, in the second year I will lost 50,000 dollars (50% of 100K). In the third... ok, ok, easy... When I buy stock, my...

I'm looking for a website like this http://etn.io that allow me create my own diagram. Someone know?

No more answers??

##r = \sqrt{x^2 + y^2}## ... ##(y = ax+b)## ##r = \sqrt{x^2 + (a x + b)^2}## ... ##(x = r \cos(\theta))## ##r = \sqrt{(r \cos(\theta))^2 + (a (r \cos(\theta)) + b)^2}## https://www.wolframalpha.com/input/?i=r+=+sqrt((r+cos(t))²+++(a+r+cos(t)+++b)²)+solve+for+r "r = sqrt((r cos(t))² + (a r...

Because I want (actually, I need, due the technical difficulties) to express ##r = r(\theta)## EDIT: I can't to express an implicit funcion in polar or log polar mode...

I know the concepts of conformal mapping and complex mapping but I didn’t see none explanation about how apply this ideia and formula for convert a curve, or a function, between different maps. Look this illustration… In the Cartesian map, I basically drew a liner function f(x) = ax+b...

We know that in the continuous math, e is special number because if f(x) = e^x, so f'(x) = f(x). But in discrete math, what's the constante base that satisfies this condition? Is not the 2? I. e. f(n) = 2^n ? Thanks,

Thank you very much! ... Can be too this diference equation: Af(n-2) + Bf(n-1) + Cf(n) = 0 ?

See my question in this topic: https://www.physicsforums.com/threads/3x3-matrix.851891/ My question is the same and I still I don't know the answer...

An ODE of second order with constants coefficients, linear and homogeneous: Af''(x) + Bf'(x) +Cf(x) = 0 has how caractherisc equation this equation here: Ax^2 + Bx +C = 0 and has how solution this equation here: f(x) = a \exp(u x) + b \exp(v x) where u and v are the solutions (roots) of the...

Exist solution for SAR(n+1) in this equation: https://en.wikipedia.org/wiki/Parabolic_SAR ? I want to eliminate SAR(n), but I never saw this kind of equation before...

A quadratic equation in this format x² - 2 A x + B² = 0 can be modified and expressed like: x² - 2 (u) x + (u² - v²) = 0. The roots x1 and x2 are therefore: x_1 = x_1(u,v) = u + v x_2 = x_2(u,v) = u - v Or: x_1 = x_1(a, b) = \frac{a+b}{2} + \frac{|a-b|}{2} x_2 = x_2(a, b) = \frac{a+b}{2} -...

Hi! I'd like to know of f'(x)/f(x) has some special interpretation, some physics or math concept related. This ratio appears many times in control theory...

I know several math formulas, like which I will write below. \int_{x_0}^{x_1} f(x) dx \frac{\int_{x_0}^{x_1} f(x) dx}{x_1-x_0} \frac{\int_{x_0}^{x_1} f(x) dx}{2} f(x_1) - f(x_0) \frac{f(x_1) - f(x_0)}{x_1-x_0} \frac{f(x_1) - f(x_0)}{2} \frac{f(x_1) + f(x_0)}{2} And I know too that...