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View:  Topic list, Topic summary Topics 1 - 10 of 40221  Older »
Description: Mathematica discussion group. (Moderated)
 

Question about ColorFunction 
  Anyone explain to me how ColorFunction works? Why Plot3D[Sin[x + y], {x, 0, 3}, {y, 0, 3}, ColorFunction -> (Hue[Sin[#1 + #2]] &)] and Plot3D[Sin[x + y], {x, 0, 3}, {y, 0, 3}, ColorFunction -> (Hue[#3] &)] return different color distributions?
By Jee Lou  - May 23 - 1 new of 1 message    

Slow Locator in Manipulate 
  The following is a simple example of the use of a Locator on a graphic: p1 = ContourPlot[ Sin[x y], {x, -3 \[Pi], 3 \[Pi]}, {y, -3 \[Pi], 3 \[Pi]}, ContourShading -> False]; Manipulate[ Show[p1, Graphics[{Red, AbsolutePointSize[5], Dynamic@Point[pt1]}], PlotRange -> {{-3 \[Pi], 3 \[Pi]}, {-3 \[Pi], 3 \[Pi]}}],... more »
By Kevin J. McCann  - May 23 - 1 new of 1 message    

Data of non-trivial NonLinearFit 
  Sorry, the data are below.... Hi, I've got a problem with a nonlinear fit. My function is this: B1= a1+b1/tr+c1/tr3 B2= a2+b2/tr+c2/tr3 B3=a3+b3/tr+c3/tr3 Btot=x*B1+y*B2+z*B3 I've got two dataset (some values are given below), one containing the Btot and Tr ed one containing x,y,z. My target is to make a regression to obtain the values a,b,c of every equation using only one regression.... more »
By Meriens  - May 23 - 1 new of 1 message    

Fourier DFT scaling problem 
  Hi all. I hope someone can help me with what seems to be a fairly elementary problem, nevertheless I have spent a good deal of time trying to come to a solution without any success. I am fairly new to the Fourier transform. My problem is that the output of the Fourier[] command has a scaling dependency on my sampling parameters which I cannot figure out how to remove.... more »
By Arthur  - May 22 - 2 new of 2 messages    

Finding the real part of a symbolic complex expression 
  ... Assuming[Element[{a, b, c, d}, Reals],Simplify[Re[Expand[(a + I b) (c + I d)]]]]
By Cisco Lane  - May 22 - 1 new of 1 message    

Non-trivial Non- linear fit 
  Hi, I've got a problem with a nonlinear fit. My function is this: B1= a1+b1/tr+c1/tr3 B2= a2+b2/tr+c2/tr3 B3=a3+b3/tr+c3/tr3 Btot=x*B1+y*B2+z*B3 I've got two dataset (some values are given below), one containing the Btot and Tr ed one containing x,y,z. My target is to make a regression to obtain the values a,b,c of every equation using only one regression.... more »
By Meriens  - May 22 - 2 new of 2 messages    

rHelp Finishing Mathematica Program 
  ... ... ... ... ... With Mathematica, you probably do not need an explicit loop. Your problem sounds like it is made to order for NestWhile. Look at the documentation for examples. ... If I recall the ground rules for this group correctly, the answer is you cannot do this. The best workaround is to post a... more »
By Bill Rowe  - May 22 - 2 new of 2 messages    

Truncated inverse Wishart distribution 
  I would like to calculate the mean of a truncated inverse Wishart distribution? I.e., if B is an inverse Wishart variable, then I'd like to calculate E(B|B<W), where B<W means that W-B is positive definite. I have the answer for the degenerate case where B and W are scalars -- that is, where B is an inverse chi-square variable and W is a scalar constant. The answer then is a ratio of gamma functions, and you can get it using the TruncatedDistribution function and the InverseChiSquareDistribution.... more »
By paul  - May 21 - 1 new of 1 message    

rHelp Finishing Mathematica Program 
  This project involves finishing the Mathematica program which I started. A loop must be added to the program. The trial value for k is to be replaced by the calculated value of k and then recalculated in the loop, over and over, until the error between the trial value of k and the calculated value of k is less... more »
By ivantulin@yahoo.com  - May 21 - 1 new of 1 message    

help with layman terms algorithm development? 
  ok, i have a fairly simple problem, that will probably look really complicated in a computer solving algorithm. i'm not trying to implement it into mathematica yet i just want to get an idea of what it would look like in general terms here's the problem: you have a room that is 130 feet wide and 65 feet long... more »
By luke wallace  - May 21 - 1 new of 1 message    

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