math

[deleted_user0]

How should I do this? I found gradient but what now? Should I find total differential with all values up 10% and divide everything -10%?

[noissance]

Check this link out:
http://math.sci.ccny.cuny.edu/document/show/2213

Problem 1.15 will help you to solve this problem.

[iNcog]

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[iNcog]

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[iNcog]

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[noissance]

? This is baby steps compared to optimization algorithms i've used in matlab and mathematica. This is nothing but application of the total differential. It only really shows the benefit when used with differential equations. It is just a classic math problem: use the brain-challenging method to solve the problem instead of something simple like plug/chug. As for what i use at work, it's much different than this, as i use FEA which relies on tensor operators and spits out the resulting tensor for my engineering calculations.

[deleted_user0]

I tried to follow this 1.15 exercise but still can't get the right answer. Should be 18,46%. Also does this 10% mean +-5% or +-10%

Could you please try to solve this one and send me the solution?

[Vinyanyérë]

10% means +/- 10%

Too lazy to use LaTeX, so I'm just going to write it out here. I'm renaming the variables x_1, x_2, x_3 to x, y, z, respectively.

dC = (2x+y)dx + (4y+x+z)dy + (6z+y)dz

Substitute x = 20, y = 10, z = 10, dx = 2, dy = 1, dz = 1 to get dC = 240

Compute C(20,10,10) = 1300

240/1300 = 18.46%

[iNcog]

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[iNcog]

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[noissance]

10% means +/- 10%

Too lazy to use LaTeX, so I'm just going to write it out here. I'm renaming the variables x_1, x_2, x_3 to x, y, z, respectively.

dC = (2x+y)dx + (4y+x+z)dy + (6z+y)dz

Substitute x = 20, y = 10, z = 10, dx = 2, dy = 1, dz = 1 to get dC = 240

Compute C(20,10,10) = 1300

240/1300 = 18.46%

wait so you just divide dC by 1300?

why does noissance's 1.15 exercise talk about distance?

Typo, 1.16 is the problem you need to look at and yeah like above ^

Error = dC(20,10,10)/C(20,10,10)

[deleted_user0]

Where this 1300 comes from?
I'm rly noob at this stuff

edit: aaa just value of function with plugged it shit. was just confused. thanks a lot!!!

[Vinyanyérë]

10% means +/- 10%

Too lazy to use LaTeX, so I'm just going to write it out here. I'm renaming the variables x_1, x_2, x_3 to x, y, z, respectively.

dC = (2x+y)dx + (4y+x+z)dy + (6z+y)dz

Substitute x = 20, y = 10, z = 10, dx = 2, dy = 1, dz = 1 to get dC = 240

Compute C(20,10,10) = 1300

240/1300 = 18.46%

wait so you just divide dC by 1300?

why does noissance's 1.15 exercise talk about distance?

It's solving a slightly different problem. I didn't actually verify that 240/1300 is solving what the question is asking for, I'm just assuming it is since it divides into the answer.

[Vinyanyérë]

1300 is obtained by evaluating C at the outputs x = 20, y = 10, z = 10

[iNcog]

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[noissance]

1300 is when you plug in 20,10,10 to the original function. dC gives you the approximate change in cost when you factor in the error. dx1 = 0.1 x1, dx2 = 0.1 x2, dx3 = 0.1x3.

@iNcog

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i need more lighting in the room, cant see the keyboard properly

@Vinyanyérë

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what do you study/have studied?

[iNcog]

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[Vinyanyérë]

@noissance

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I was ECE+Math for undergrad, now EE for grad school. Though I'm leaving grad school soon to do other stuff.

[noissance]

Nice, i am doing MSE in grad school atm.

[Vinyanyérë]

Good stuff. Masters or Ph.D.? What's your research subject?

[noissance]

Finishing up my masters portion of grad school, going for a doctorate. My research is in the field of thin film deposition atm, i want to research magnetic nanoparticles next.

[deleted_user]

Bunch of academics in AoE I see

[Gendarme]

Noissance is just talking shit. He works as McDonald's.

[noissance]

Noissance is just talking shit. He works as McDonald's.

Ahem, i dont work at McDonald's. I am my professor's Teaching Assistant (slave).

[deleted_user]

My TA for both of my engineering courses this year was in my spring break group last year so that made my HW grades a bit better this semester #networking