/sci/ - Science & Math » Thread #12219749

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Anonymous Sun 11 Oct 18:18:23 2020 No.12219749 View Reply Original Report

Quoted By: >>12219765 >>12220006 >>12220077 >>12220625 >>12220669 >>12221492 >>12222990

Now THAT's a big matrix. I wonder how long it would take to calculate the inverse by hand.

From: https://en.wikipedia.org/wiki/Redheffer_matrix

Anonymous

Anonymous Sun 11 Oct 2020 18:24:34 No.12219765 Report

Quoted By: >>12219769

>>12219749
The matrix is only ones and zeroes and is lower triangular. So it may take some effort to find the inverse by hand but it wont be that difficult. It will however be extremely tedious.

Given my distractibility and my distaste for such tasks, it will likely take me 45mins-1hr to calculate this inverse by hand.

Anonymous

Anonymous Sun 11 Oct 2020 18:26:07 No.12219769 Report

Quoted By: >>12220110

>>12219765
Why not do something else then if you don't want to do it?

Anonymous

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Anonymous Sun 11 Oct 2020 20:03:33 No.12220006 Report

Quoted By: >>12220030

>>12219749
>THAT's a big matrix

Anonymous

Anonymous Sun 11 Oct 2020 20:15:04 No.12220030 Report

Quoted By: >>12222057

>>12220006
101 u

Anonymous

Anonymous Sun 11 Oct 2020 20:42:52 No.12220077 Report

Quoted By:

>>12219749
Not long. You just row reduce keeping track of the steps, and the work is mostly done since it's lower triangular.

Anonymous

Anonymous Sun 11 Oct 2020 20:47:20 No.12220087 Report

Quoted By: >>12220173

Post more interesting matrices (preferably large).

Anonymous

Anonymous Sun 11 Oct 2020 20:57:47 No.12220110 Report

Quoted By:

>>12219769
I wouldn't, I was just answering the question.

We have computers for a reason.

Anonymous

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Anonymous Sun 11 Oct 2020 21:12:48 No.12220173 Report

Quoted By: >>12222969

>>12220087
i'd post the thicc 150000x200000 linear systems i solve on a regular basis in seconds in my lab, but that wouldn't even fit in an image file

Anonymous

Anonymous Sun 11 Oct 2020 23:43:31 No.12220625 Report

Quoted By: >>12220669

>>12219749
>by hand
unironically, thats math pedagogy in a nutshell. to give students a bunch of stupid number crunching problems and then wonder why most of them hate math.

Anonymous

Anonymous Sun 11 Oct 2020 23:54:59 No.12220669 Report

Quoted By: >>12220685 >>12220697

>>12219749
It takes me around 1 second to find the inverse of a 1x1 matrix. By extrapolation it would take me about 400 seconds to find the inverse of this matrix.

>>12220625
This is true for highschools, but not for higher education. In one of my algebra classes we showed the existence of the Jordan normal form and did a very smooth 0 examples

Anonymous

Anonymous Sun 11 Oct 2020 23:59:55 No.12220685 Report

Quoted By:

>>12220669
i don't know, maybe if you are a math major at a decent school, otherwise it is same soul crushing routine of solving countless derivatives and integrals and differential equations which are always reduced to a bunch of tedious fractions and quadratic equations and you can't use a calculator which is bullshit. it is not math, it is just dumb calculations.

Anonymous

Anonymous Mon 12 Oct 2020 00:06:04 No.12220697 Report

Quoted By: >>12221649 >>12222102

>>12220669
even in higher education it's true m8
learning the majority of integrals is absolutely retarded in calc 2 (integral calculus for non burgers)
at most u substituin and integration by parts are all you need for hand integration
calc 2 doesn't even include numerical calculation of integrals

Anonymous

Anonymous Mon 12 Oct 2020 04:45:13 No.12221492 Report

Quoted By:

>>12219749
That looks like a Redheffer to solve by hand, though...

Anonymous

Anonymous Mon 12 Oct 2020 05:32:53 No.12221649 Report

Quoted By:

>>12220697
>higher education
>calc 2

Anonymous

Anonymous Mon 12 Oct 2020 09:03:34 No.12222057 Report

Quoted By:

>>12220030
(4)_10 == (100)_2

Anonymous

Anonymous Mon 12 Oct 2020 09:22:32 No.12222102 Report

Quoted By:

>>12220697
My calc 2 class covered Simpson's and trapezoid methods for approximating integrals.

Anonymous

Anonymous Mon 12 Oct 2020 16:23:30 No.12222969 Report

Quoted By:

>>12220173
>150kx200k
>but that wouldn't even fit in an image file
is that so? How large do the numbers get?

Anonymous

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Anonymous Mon 12 Oct 2020 16:27:36 No.12222990 Report

Quoted By:

>>12219749
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