Maths Symbols

∴ – therefore

|x| = Euclidian Length i.e. the pythagorean hypoteneuse √((x’-x)^2+(y’-y)^2)

≈ – approximately equal to

⇒ implies

∀ – for all, any & each… e.g. ∀ x: P(x) for all x P is true

∃ – there exists a… e.g. ∃ x: P(x) There is an x such that P is true

ℝ – Real numbers , x ∈ ℝ – x is a real number

∑ – summation i.e. \sum_{k=1}^{n}{a_k} means a_1 + a_2 + \cdots + a_n.

∏ – product \prod_{k=1}^na_k means a_1 a_2 \dots a_n.

Δ – delta , change in… Δx – change in x

∂ – partial derivative i.e. ∂E/∂y – Change in E as y changes. Also the slope or gradient of the line (E,y). Useful for Stchastic Gradient Descent in Neural Net Backpropagation.

T – Matrix Transpose — AT means A, but with its rows swapped for columns. Also A’

MathML – does it work – http://en.wikipedia.org/wiki/MathML ? not in Firefox 18.0.2 OOTB but it’s supposed to. grrrrrr

math mode=”display” xmlns=”http://www.w3.org/1998/Math/MathML”

Firemath ? www.firemath.info/examples/ — doesn’t work in FF 18

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