Matlab

Plotting using loops
I have to plot x versus y and I have both the variables defined y is a vector of length 3619 and x is also 3619. x is the amount of rows and I want to plot (x,y) going in intervals of 100 rows. i.e. 1:100 2:101 3:102. any suggestions on how to do this. ... 5 Aug 2010 01:35

Using Find within "sub-array"
Here is the issue I am having. I have an mxn matrix, that is very large. I would like to use the find command but it is pretty slow for large arrays... but I have noticed that I get a substantial improvement in speed when my mxn matrix is smaller. So now I use the find command on a much smaller subset of the initi... 5 Aug 2010 10:13

decompose strain tensor
Hi, I am in need of expressing a strain field in a different coordinate system (new coordinate system is rotated w.r.t. the old one). The strain components are available to me in the old coordinate system (E11, E22, E33, E12, E13, E23), and I just need to re-write it in the new coordinate system. Alternatively, I ca... 5 Aug 2010 14:39

Mathematica 7 bug - NIntegrate (Sin, Cos, Sqrt)
NIntegrate[ 1/Sqrt[(Cos[z] + Cos[2 z] + Cos[3 z] + Cos[4 z])^2 + (Sin[z] + Sin[2 z] + Sin[3 z] + Sin[4 z])^2], {z, 0, Pi/2}] -> 13.2482 and no warning is given. This integral, obviously, diverges. Maple 14 handles this OK. evalf(Int( 1/sqrt((cos(z)+cos(2*z)+cos(3*z)+cos(4*z))^2+ ... 5 Aug 2010 13:32

number of operands
Hello , Is there anyway to count the number of operands in Matlab? For example, If, u = [1, 4, 9] The number of operands n is: n = 3. How can this be done. thanks. ... 4 Aug 2010 22:21

Input argument "Yd" is undefined.
Hi, Can someone check my code, and error like below cameout when running the program. What should I do to correct it. ??? Input argument "Yd" is undefined. Error in ==> sb_inputy at 8 e1 = Yd(1) - y(1); Error in ==> y_position at 46 u=sb_inputy(t_current,y,k1,k2,k3,k4,k5,m2,Ix,Iy,Iz,l,Xd,Yd); ---------... 5 Aug 2010 10:13

piecewise polynomial - no shift option
I am currently working on a program in matlab where the use of piecewise polynomials would be quite convenient. Unfortunately, as I recently discovered, the piecewise polynomial object type (pp) included with matlab takes the constants for the polynomail you pass it, assumes those coefficients are for a polynomial c... 13 Aug 2010 01:41

An exact simplification challenge - 102 (Psi, polylog)
Hello, Mathematica: PolyGamma[1, 1/6] + 9 PolyGamma[1, 1/3] - 9 PolyGamma[1, 2/3] - PolyGamma[1, 5/6] - 48 I Sqrt[3] PolyLog[2, ((2 + 3 I) - (1 + 2 I) Sqrt[3])/2] + 48 I Sqrt[3] PolyLog[2, (1 - 3/2 I) - (1/2 - I) Sqrt[3]] Maple: Psi(1,1/6)+9*Psi(1,1/3)-9*Psi(1,2/3)-Psi(1,5/6)- 48*I*sqrt(3)*polylog(2,1+3... 4 Aug 2010 22:21

Integral Problem
Hello. I want to find value of integral from 0 to 1 exp(t*sin(x))*dx with function int I can find integral from 0 to 1 exp(sin(x))*dx But if I add independent variable t, than I receive an error from function int() How can I evaluate that integral? Thank you. ... 5 Aug 2010 22:28

check for existence of user define object in array
Hi, I want to check for the existence of a user defined object in an array of these items. Something like this An array containing Object(1) Object(23) Object(35) Is there a matlab command to check for the existence of Object(35) in this array without iterating through its elements? ... 4 Aug 2010 23:26