anyone IN DH hill right now know how to use matlab? I could use some help if you guys feel like being nice.

6/11/2008 8:52:33 PM

dh hill during the summer is for dorks and the homeless.

6/11/2008 8:59:37 PM

good luck

6/11/2008 8:59:47 PM

so i take it thats a no. Anyone on here want to help me. I think i've found the problem but i don't know how to fix it.

6/11/2008 9:01:01 PM

Quote :

"GOOD LUCK FUCKER"

6/11/2008 9:01:30 PM

that shit is funny

6/11/2008 9:02:12 PM

i'm in the unity lab

6/11/2008 9:03:21 PM

haay funkwads

6/11/2008 9:04:17 PM

^where in the unity lab?

6/11/2008 9:04:44 PM

I'm over here ........I'll wave at u ok?

6/11/2008 9:05:18 PM

dude i'm joking

i'm not in the unity lab

I graduated last year.

[Edited on June 11, 2008 at 9:06 PM. Reason : f]

6/11/2008 9:05:22 PM

how the hell am i supposed to know that?

[Edited on June 11, 2008 at 9:07 PM. Reason : damn]

6/11/2008 9:07:02 PM

depends on your problem

and if i can solve it from my house in brier creek

6/11/2008 9:07:34 PM

I dont have matlab

6/11/2008 9:08:11 PM

I just learned matlab yesterday

>> clear
m1=150/32.2; %slugs
m2=3; %slugs
Fo=50; %pounds
w=[0:1:100]; %rad/s
massmatrix =[m1 0
0 m2];

k1=1.4400e+004;
k2=500;

springmatrix =[k1+k2 -k2
-k2 k2];

Zmatrix=massmatrix.*-(w.^2) <----- I think thats the problem right there.
??? Error using ==> times
Matrix dimensions must agree.

[Edited on June 11, 2008 at 9:08 PM. Reason : learnimucation]

6/11/2008 9:08:13 PM

the answer is X = 3

6/11/2008 9:08:55 PM

good luck with that

6/11/2008 9:09:28 PM

X = 3 radians.....my bad

6/11/2008 9:09:32 PM

post the damn problem and someone might be able to help you sooner, dumbass

Also, fuckwads lacey say's hi.

[Edited on June 11, 2008 at 9:10 PM. Reason : finally]

6/11/2008 9:09:45 PM

HAAAAY

6/11/2008 9:10:12 PM

hiiiiiiiiiii


hows married life?

6/11/2008 9:10:32 PM

^^^ you should read before posting

Shouldn't you be working not onTdub?



[Edited on June 11, 2008 at 9:11 PM. Reason : k]

6/11/2008 9:10:40 PM

pads

6/11/2008 9:11:32 PM

you have to use dot times or something like that

i can't really remember, only that there is a different way to multiply specifically for matrices

[Edited on June 11, 2008 at 9:13 PM. Reason : oh you already are]

6/11/2008 9:12:01 PM

problem is with this command

massmatrix.*-(w.^2)

i'm gonna see what i can do with it...what is it supposed to do?

6/11/2008 9:12:32 PM

I think i am using dot times.

6/11/2008 9:12:44 PM

why the fudge do they teach this crap if u dont use it on the job and no one even remembers how to do it? I mean shit guys.

6/11/2008 9:13:36 PM

clear
m1=150/32.2; %slugs
m2=3; %slugs
Fo=50; %pounds
w=[0:1:100]; %rad/s
massmatrix =[m1 0
0 m2];

k1=1.4400e+004;
k2=500;

springmatrix =[k1+k2 -k2
-k2 k2];

Zmatrix=massmatrix.*-(w.^2)+springmatrix
Zdet=det(Zmatrix)

a=m1*m2
b=m1*k2+m2*(k1+k2)
c=(k1+k2)*k2-k2^2

naturalfreq1=((-b+(b^2-4*a*c)^.5)/(2*a))^.5
naturalfreq2=((-b-(b^2-4*a*c)^.5)/(2*a))^.5


X1=((-(w.^2)*m2+k2)*Fo)./Zdet;
X2=(-k2*Fo)./Zdet;

plot(w,abs(X2))
axis([0 100 -.4 .4])
xlabel('Omega')
ylabel('X')

Its for vibrations. i basicaly need a graph of w versus X1 or X2

6/11/2008 9:14:03 PM

Welcome to college.

6/11/2008 9:14:16 PM

try splitting them up instead of doing all the functions in one statement... limits the opportunity for syntax errors.

i.e.

x=(-(w.^2));
y=massmatrix.*(x);

zmatrix=y+spring;

[Edited on June 11, 2008 at 9:16 PM. Reason : f]

6/11/2008 9:14:20 PM

^i did and that's what the error is

i don't know shit about matrices though...your 'w' comes out as

  Columns 1 through 13 

     0     1     2     3     4     5     6     7     8     9    10    11    12

  Columns 14 through 26 

    13    14    15    16    17    18    19    20    21    22    23    24    25

  Columns 27 through 39 

    26    27    28    29    30    31    32    33    34    35    36    37    38

  Columns 40 through 52 

    39    40    41    42    43    44    45    46    47    48    49    50    51

  Columns 53 through 65 

    52    53    54    55    56    57    58    59    60    61    62    63    64

  Columns 66 through 78 

    65    66    67    68    69    70    71    72    73    74    75    76    77

  Columns 79 through 91 

    78    79    80    81    82    83    84    85    86    87    88    89    90

  Columns 92 through 101 

    91    92    93    94    95    96    97    98    99   100

6/11/2008 9:14:59 PM

this thread started out potentially quite funny, and went to shit in about 2 and half minutes.

6/11/2008 9:15:02 PM

i tried that its Zmatrix=massmatrix.*-(w.^2) that is giving me the problem. I think i'm not making a correct matrix for w

6/11/2008 9:15:34 PM

so you're trying to multiply a 2x2 matrix by a 13x6 ish matrix

6/11/2008 9:16:34 PM

i'm trying to use w as a variable from 1-100

6/11/2008 9:17:18 PM

BWN?

6/11/2008 9:17:18 PM

I have used matlab in my jobs. Its useful for communications and signal processing work.

6/11/2008 9:17:32 PM

so the 2x2 multiplied by 1, then 2, then 3....then 99, then 100 (squared, negative)

?

[Edited on June 11, 2008 at 9:18 PM. Reason : l]

6/11/2008 9:18:00 PM

^yup ^^^ sure

[Edited on June 11, 2008 at 9:18 PM. Reason : ^]

6/11/2008 9:18:24 PM

lets do lunch k?

6/11/2008 9:23:10 PM

i think you're doing it wrong



lemme see what i can look up

(bored as fuck)

6/11/2008 9:26:04 PM

yeah you're trying to do a for...end loop if i'm not mistaken

6/11/2008 9:35:26 PM

^what?

6/11/2008 9:36:45 PM

for x>100
do
...

that

6/11/2008 9:39:04 PM

^ i don't care about x>100 i only car about 0<x<100

w=[0:1:100]; its probably how i'm doing that and i don't knwo how to do do-loops in matlab.

6/11/2008 9:43:35 PM

i was thinking something along the lines of

for w = 1:100
Zmatrix=massmatrix.*-(w.^2)+springmatrix
Zdet=det(Zmatrix)

end

but its returning a plot of two points, one of X1 and one of X2

6/11/2008 9:44:14 PM

^thats actually kind of what i need.


Its still telling me the same error.

[Edited on June 11, 2008 at 9:49 PM. Reason : ff]

6/11/2008 9:46:26 PM

i think you missed a class or two

I believe there are supposed to be or more files that contain reference forumulas.

here's an example of one of my working matlabs. Where it says File: is a new file, so everything from the clc to the next --- is the file.

------
File: Ex1.m

    clc
    clf
    clear
    global m Cp U R Th Ti
    
    m=1;
    Cp=0.75;
    U=24.0;
    R= (0.005);
    Th = 80;
    Ti= 0;    
    
    zo = 0;
    zf = .50;
    zspan = [zo, zf];
    T0 = [Th];
        
    [z, T] = ode15s('Ex14drv', zspan, T0);

 
    for i = 1:12
        Ta(i,1) = Ex14an(z(i));
    end

    plot (z, T(:,1), '-', z, Ta(:,1), '+'), title ('Temperature vs. Distance'),... 
         legend ('T', 'Ta'), xlabel ('z(m)'),... 
         ylabel ('T(C)');
--

File: Ex1an.m

    function y = Ex14an(z)
    global m Cp U R Th Ti
    
    y = Ti + (Th-Ti)*exp(-U*2*pi*R*z/(m*Cp));
    
--

File: Ex1drv.m

    function dT = Ex14drv(z,T)
    global m Cp U R Th Ti
   
    dT = (-U*(2*pi*R)*(T-Ti))/(m*Cp);

----

6/11/2008 9:53:35 PM

^?? I never took classes in matlab just fortran.

[Edited on June 11, 2008 at 10:09 PM. Reason : k]

6/11/2008 9:57:36 PM

well shit, i dunno

6/11/2008 10:20:05 PM