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Thank you everyone for posting errors! I have tried to fix (most) of them!

by MathOnlineMathOnline, 18 Feb 2018 03:45

Thanks, this has been fixed!

by MathOnlineMathOnline, 18 Feb 2018 01:19

Thanks! This should corrected now and I'm glad you like the site!

by MathOnlineMathOnline, 18 Feb 2018 01:17

Corrected, Thank you, and glad you like the site (: !

by MathOnlineMathOnline, 18 Feb 2018 01:04

Corrected, Thank you!

by MathOnlineMathOnline, 18 Feb 2018 00:46
Brooks' Theorem (guest) 18 Feb 2018 00:39
in discussion Hidden / Per page discussions » Submitting an Error on Math Online

There's a typo in the third subsection of the Theorem 1: "can can"

I suggest to clarify the Theorem 1 proof, especially the inductive step which is a little messy

Thanks in advance for your work!

Mik

by Brooks' Theorem (guest), 18 Feb 2018 00:39

There is an error, it should say F^2, not F^3.
in the first subsection Vector Subspace Sums

… For example, consider the subspaces U1={(x,0):x∈F} and U2={(0,y):y∈F} of *F3*. We denote the sum of these subspaces U1+U2={(x,0)+(0,y):x,y,∈F}={(x,y):x,y∈F}, which is also a subspace of *F3*. <—— These should be F^2.

vector subspace sums by Max JerryMax Jerry, 10 Feb 2018 01:57
Abdu Magdy (guest) 28 Jan 2018 18:00
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Sequences and Series of Complex Numbers:

In the example of the convergence of the sequence {[(2+1)i]/[n+1]}, you said "We claim that this series converges to 0" while it's supposed to converge to (2+i).

by Abdu Magdy (guest), 28 Jan 2018 18:00
Matthew (guest) 18 Jan 2018 01:00
in discussion Hidden / Per page discussions » Submitting an Error on Math Online

Page: "The Invertibility of a Matrix"

Part of the proof for the A^-1 formula (namely (5)), it should be (ad-bc)/(ad-bc)=1, not (-cd+ab)/(ad-bc)=1

by Matthew (guest), 18 Jan 2018 01:00
Ulrik (guest) 16 Jan 2018 15:55
in discussion Hidden / Per page discussions » Submitting an Error on Math Online

It appears that Z+ and R+ have been mixed up in section "Equality of Sets" on page "Set Notation"

by Ulrik (guest), 16 Jan 2018 15:55

There's a typo in the article titled Lagrange's Identity. The words "righthand" and "lefthand" should be switched in the proof.

by Au79enAu79en, 07 Jan 2018 11:30

There's a typo while calculating ||r'(t)||, that is the magnitude of the tangent vector. You have written,

(1)
\begin{align} \| \vec{r'}(t) \| = \sqrt{R^2 \sin ^2 t + R^2 \cos ^2 t} = \sqrt{R^2} = R^2 \end{align}

It should be $\sqrt{R^2} = R$
obviously.

Meh (guest) 05 Dec 2017 14:52
in discussion Hidden / Per page discussions » Submitting an Error on Math Online

On the tietze-transformations page, in the example, the last line deletes the variable a, which changes the group. Instead I think the variable z should have been added first, with z=a.

by Meh (guest), 05 Dec 2017 14:52
Chaaben (guest) 29 Nov 2017 14:37
in discussion Hidden / Per page discussions » Submitting an Error on Math Online

Hi,

on the page: Properties of Adjoints of Linear Maps

Proposition 3: Proof: We note that <(T*)*(v),w> = <v,(T*)*(w)>

I think it should be: <(T*)(v),w> = <v,(T*)*(w)>

Thank you

by Chaaben (guest), 29 Nov 2017 14:37
Chaaben (guest) 28 Nov 2017 13:42
in discussion Hidden / Per page discussions » Submit a Bug Report

Hi,

on the page: Eigenvalues and Eigenvectors Examples 1

In the Example 3, the converse direction of the proof: … Since[[ T^{-1}$ is also …

Thank you

by Chaaben (guest), 28 Nov 2017 13:42
Chaaben (guest) 27 Nov 2017 19:12
in discussion Hidden / Per page discussions » Submitting an Error on Math Online

Hi,

on the page: Linear Maps

An equivalent definition … T(u+v) + T(u) + T(v) (Additivity)

I think it should be, T(u+v) = T(u) + T(v) (Additivity)

Thank you

by Chaaben (guest), 27 Nov 2017 19:12
Chaaben (guest) 27 Nov 2017 15:45
in discussion Hidden / Per page discussions » Submitting an Error on Math Online

Hi,

on the page: Range of a Linear Map

Proof of Lemma 2, the fifth point: From Lemma 1, we have that 0W = range(T).

I think it should be, 0W ∈ range(T).

Thank you

by Chaaben (guest), 27 Nov 2017 15:45
Chaaben (guest) 27 Nov 2017 14:01
in discussion Hidden / Per page discussions » Submitting an Error on Math Online

Hi,

on the page: Eigenvalues and Eigenvectors Examples 3

In Example 1: 3y = λ(λy
2)

I think it should be 3y = λ(λy)/2

Thank you

by Chaaben (guest), 27 Nov 2017 14:01
Chaaben (guest) 26 Nov 2017 10:31
in discussion Hidden / Per page discussions » Submitting an Error on Math Online

Hi,

on the page: Injective, Surjective, and Bijective Functions

At the bottom of the page: In the examples from earlier, we see that f is both injective and surjective, so g is bijective.

I think it should be, f is bijective.

Thank you

by Chaaben (guest), 26 Nov 2017 10:31
Chaaben (guest) 25 Nov 2017 13:35
in discussion Hidden / Per page discussions » Submitting an Error on Math Online

Hi,

on the page: Self-Adjoint Linear Operators

The example T(x,y)=(2x+3y,3x+2y): Note that T(1,0)=(2,3) and T(0,1)=(3,0).
So T(0,1) should be equal to (3,2).

Thank you

by Chaaben (guest), 25 Nov 2017 13:35
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