Math Help Forum - Mathematics Software Discussion

Please help me construct a graph...

elninio — Fri, 20 Nov 2009 20:57:36 GMT

I have no experience with this sort of problem.

I've only ever made simple graphs before. This one requires special computer software.

For now, the problem is simple...

I have derived a formula for a simple model of a star:

;

I need to make a graph of a vs b.

This is where I'm begging you to help me. What (free) program could I use? Could anyone provide instructions on how to graph this with the program?

I thank you very very much in advance!

Graph

nikk — Fri, 20 Nov 2009 17:02:01 GMT

any one have idea, what kind of software to plot the following graph?

thank for your help and time

Attached Thumbnails

DSP in Matlab

luckyvictor — Thu, 19 Nov 2009 15:49:40 GMT

Hello

I am new to this forum, and I am a beginner to Matlab.

I have a test wav file that Matlab can read, and I would like to have a windowing function to capture a very short time of the test.wav .

I have already set up the windowing function, which is hann(128), but I have no idea how to use it to caputer a time slide in my test.wav, let say I would like to capture at time 4s in my test.wav.

So my question is how to move this hann(128) to center at 4s of my test.wav, and also how to multiply them? as I got error saying something like wrong dimension.

Thank you very much in advance

Matlab Chebyshev Points

muq08 — Wed, 18 Nov 2009 18:29:59 GMT

Matlab Simpsons Rule and Midpoint Rule

muq08 — Wed, 18 Nov 2009 18:27:09 GMT

Document Conversion

lsbora — Wed, 18 Nov 2009 11:20:52 GMT

How Can I Scan Document Into Microsoft Word 2003 And Have It Look The Same as The Original?

SVD inconsistency?

adikash — Wed, 18 Nov 2009 03:59:21 GMT

Cannot figure out why the Matrix S1 and S2 differ. Seems to work when the Matrix S1 is a random matrix (rand) but when the source is a wave file which has been made into a matrix using the Short time Fourier transform, S1 and S2 differ and i cannot seems to get back the original matrix S1. Anybody has any clue Why this happens?

y = wavread('source.wav');
S1= myspectrogram(y); % Generic routine to get the STFT
[U S V]=svd(S1);
S2= U*S*(V');

If anybody has any clue plz reply. Thanks for looking.

Converting an R-program to MATLAB

turfiemurphy — Tue, 17 Nov 2009 15:54:58 GMT

Hi guys,

Can anyone help we write this program in MATLAB:

n <- 5000;
m <- array(rnorm(n^2),c(n,n));
m2 <- (m+t(m))/sqrt(2*n);# Make m symmetric
lambda <- eigen(m2, symmetric=T, only.values = T);
e <- lambda$values;
hist(e,breaks=seq(-2.01,2.01,.02),
main=NA, xlab="Eigenvalues",freq=F)

Any Suggestions?
Thanks

Quick MATLAB ode45 question

duma — Tue, 17 Nov 2009 04:03:58 GMT

I am using matlab for a Differential Equations course and keep getting this error when i try to plot this ode45 function:

??? Input argument "x" is undefined.

Error in ==> F at 3
xp(1)=x(2)

here is the code:
function xp=F(t,x)
xp=zeros(2,1);
xp(1)=x(2)
xp(2)=-4*x(2)-5*x(1)+10*cos(0*t)

[t,x]=ode45('F',[30,80],[0,0])
[t,x(:,1)]
plot(t,x(:,1))

I really dont know why matlab keeps telling me 'x' is undefined. Any help would be appreciated!

Matlab Matrix Compare

ul09004409 — Mon, 16 Nov 2009 20:30:25 GMT

How would you compare a 1x6 matrix to individual rows of a 10100x6 matrix. I want to know how to compare this 1x6 matrix to each of the rows of the larger matrix one at a time and then count the number of times that they are equivalent.

Maple 12

Dogod11 — Sun, 15 Nov 2009 02:50:06 GMT

Anybody know how to plot three planes in Maple on the same graph?
thanks

Math software help

extremenoob — Sat, 14 Nov 2009 14:05:30 GMT

Hey guys,

I'm currently searching for a software that can help test general statement that can also handle matrices. I want to be able to input an expression with several unknowns e.g. given the general expression A=B*C (with different unknowns inside), then have the option of trying different values of the unknowns and see if the statement is valid. Basically, what I want to do is to test the range of values of unknowns for which the statement is valid.

Do you guys know a program that can do that (or some ways)?

Extremenoob

[SOLVED] MATLAB disp() function doesn't cut it...

jfortiv — Thu, 12 Nov 2009 23:26:20 GMT

Hi,

I've been working on a simulation for a little while now. I'm to the point where I'm trying to run the simulation for a longer time period (I mean physical time represented in the simulation) than before, and I'd like to be able to track the progress of the calculation as it loops over the time vector.

I tried doing this with disp():

for j=1:length(t) %loop over time

if(rem(j-1,100)==0) %print progress every 100 time points
disp('time = ')
disp(t(j))
disp('out of ')
disp(tfinal)

Unfortunately, it seems like MATLAB performs all of the calculations in the for loop first and then spits out the disp() arguments after all is said and done. This doesn't accomplish my desired task. I'm finding this unexpected, as I've implemented similar progress tracking techniques in python using print statements.

Does anyone know how to track progress in a loop?

Thanks!

Matlab Pause and Randperm Function

ul09004409 — Thu, 12 Nov 2009 20:57:28 GMT

How would one generate a 7 digit array of numbers from 1 to 23 without repetition. Then how would you display that array with a pause between each digit? Thanks in advance

Help pl. in NDSolve Mathematica expression

Mcmohand — Thu, 12 Nov 2009 09:19:44 GMT

this may look weared but pl. help
whats wrong in following :
m = 50
e = 10^-4
c = 70*10^3
k = 1.46*10^7
M = 10
Ip = 1.6
zt = 0.1
t1 = 0
t2 = 30

s = NDSolve[{m*D[r[t]*Cos[T[t]] + e*Cos[P[t]], {t, 2}] +
c* D[r[t]*Cos[T[t]], t] + k*r[t]*Cos[T[t]] == 0,
m* D[r[t]*Sin[T[t]] + e*Sin[P[t]], {t, 2}] +
c* D[r[t]*Sin[T[t]], t] + k*r[t]*Sin[T[t]] == 0,
M + Ip* P''[t] + zt* P'[t] == 0, r[0] == 0 , T[0] == 0,
P[0] == Pi , r'[0] == 0, T'[0] == 0, P'[0] == 0 }, {r, T, P}, {t,
t1, t2}]

I am not gating ans

pl. help I am new to mathematica want to solve some problems .