/sci/ - Science & Math

I did it guys, I got a math degree

Is the universe deterministic or not?

who here is a math major but hates math?

so there was a post a few days ago, don't worry I've already checked the catalog, anyways, there was a post a few days ago about 15 or so things that every mathematician should know, does anyone happen to have that?

Was wondering if any of you could help me out some some simple recursion that I can't seem to wrap my head around

And not to beat around the bush, yes this is a homework problem, but I'm not after an answer (if that changes anything) just need a clarification

the recurrence is a(n) = na(n-1) + n!

I've thought about using generating functions but the summation of (n!)(x^n) does not converge

and so that leaves me with finding a particular solution using factorials, but I've only ever found a particular solution using exponential and polynomials, what the hell do you do with a factorial?

In complex analysis,

why is Log(z1z2) = Log(z1) + Log(z2) if and only if -pi < Arg(z1) + Arg(z2) < pi

but, Log(1/z) =/= -Log(z) anywhere?

So if most differential equations cant be solved, whats the point of them?

I have a real analysis midterm tomorrow and I have studied about 2 hours

what do?

How do you solve a problem that says
"Draw the differential equation y' = f(x,y,z), that goes through a point (value of x, value of y, value of z)"
It's prob simple as fuck but I don't seem to know what to do.

Hi /sci/,

I need help solving a PDE problem using a fast poisson solver. It involves some matlab code, but it's only a few lines. Can someone join me in here?

http://collabedit.com/qt5c8

I'll link the exact problem, I don't want someone to do it for me (and I've done about 50% of the problem), I just need someone to explain a few things, thanks.

Hi /sci/, is there anyone here familiar with introductory partial differential equations? I'm a bit behind in my summer class and I need some help with someone experienced. It also includes numerics and some matlab code. I'm not asking for anyone to do my homework, I just need help clearing some things up.

I would post it here, but I'm a bit paranoid. Anyone who can get on skype/AIM with me?

I have to write a program that calculates the smallest, largest, average and the range of a set of numbers but just can't seem to get it, what is wrong with this?

#include <iostream>

using namespace std;

int main()
{
double smallest = 0;
double largest = 0;
int count = 0;
double sum = 0;
float value;

cout << "Enter values: ";
cin >> value;

while (cin >> value)
{

if (value > largest)
{
largest = value;
}
if (value < smallest)
{
smallest = value;
}
}

count++;
sum += value;

if (count > 0)
{
double average = sum / count;
double range = largest - smallest;
cout << "The average is: " << average << endl;
cout << "The smallest is: " << smallest << endl;
cout << "The largest is: " << largest << endl;
cout << "The range is: " << range << endl;
}
else
{
cout << "You did not enter enough data" << endl;
}

return 0;
}

So I have to write this program that simulates a drunkard taking 100 steps in 4 different directions and I have to find his end point, why isn't this program working?

#include <iostream>
#include <ctime>

using namespace std;

int main()
{
int x = 0;
int y = 0;
srand((unsigned int)time(NULL));
for (int i =1; i <= 100; ++i)
{
int number;
number = rand() % 4 + 1;

if (number = 1)
{
x = x + 1;
y = y + 0;
}

else if (number = 2)
{
x = x + 0;
y = y + 1;
}

else if (number = 3)
{
x = x - 1;
y = y + 0;
}

else (number = 1)
{
x = x + 0;
y = y - 1;
}

}

cout << "(" << x << "," << y << ")" << endl;
return 0;
}

all I get is (100, 0)

much appreciated

Hello.
I need to do a project about resolution of a physical problem I choose which is governed by a parabolic PDE.

What can I choose ? I like electromagnetics and mechanics.

So my schedule for Nuc. Engineering requires only two courses (1 & 2) of "Applied Differential Equations." Does this imply that I won't actually learn the theory behind differential equations, but rather their applications alone? If so, why is this what math education has come to?

/sadface

I'm in diff eq and i'm trying to find a solution to (d^2y)/(dt^2) + sin(y) = 0

should i use variation of parameters? I really need some advice on this.

I need to learn ODE in some hours.

What resources would you recommend?
(evidently, I already have differential and integral calculus knowledge).

Thank you

I'm working with a system of differential equations atm, and just want to make sure I don't do anything stupid while doing derivations. Google results weren't particularly helpful, so I figured I'd just ask here.

Suppose I have something in the form of <span class="math">\dot{x}(t) + a(t)x(t) = b(t)[/spoiler], then one can derive that <span class="math">x(t) = I(t)^{-1} \int I(t)b(t)dt[/spoiler] where <span class="math">I(t) = e^{\int a(t)dt}[/spoiler].
Is this still a valid formula to use if we have something like <span class="math">b(t) = Ae^{at} + e^{b-c)t[/spoiler] or do I have to do something different then? I don't see why it wouldn't work, but I'd rather not spend ages working things out that aren't correct anyway.

Does anyone else really enjoy doing math?

/sci/,

I'm attempting to learn diff eq on my own and I'm really struggling with equilibrium solutions and stability. I have no trouble finding the equilibrium solutions of a given autonomous function, but I'm woefully unable to find the stability of any solution. I know what it means to be stable or unstable (at least graphically). But I have no way of finding that.. and graphing the function isn't always an option (such as when receiving an equation like dx/dt = (x-1)(x-3)^2(x-4)(x+1)^2(x).

Help?

As a baby tier biology major, if I take functional analysis, multilinear/linear algebra, harmonic analysis, and differential equations will I be at a level of competency when dealing with the more mathematical heavy aspects of my discipline?