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41653
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location Ann Arbor, MI
age 76
visits member for 1 year, 6 months
seen 8 hours ago

I am a retired software developer. I retired at the end of 2003 and since then my computer programming activities have been for recreational purposes. I find Mathematica excellent for that.

I started using Mathematica in 1997 (Ver. 3). I am currently using Ver. 9. Although I have used Mathematica for all kinds of stuff, I use it mostly to pursue my long standing interest in Euclidean geometry, both in the classical Greek synthetic form and in the more modern analytical form.


2d
comment Need to create a function to generate all permutations of Range[$n$]
14! is a rather large number, so I understand why you might not want to store all the permutations in memory. However, even if you accomplish your goal of generating the permutations one-by-one, how long do you think it will take to score more than 87 billion lists of 14 integers?
2d
revised Results of ArgMax as a function of a parameter with InterpolatingFunctions
Improved formatting
2d
revised Need to create a function to generate all permutations of Range[$n$]
General clean-up
Apr
14
comment Counting the number of instances of one sub-string within a given string within a lower- and upper-bound gap of a second sub-string
OK, I think it's clear enough now that @LeonidShifrin can solve it for us :)
Apr
14
comment Counting the number of instances of one sub-string within a given string within a lower- and upper-bound gap of a second sub-string
As I see it now, string2 is the target, the item of interest, while string1 is a landmark that only serves to define the gap. Is this correct?
Apr
14
revised Counting the number of instances of one sub-string within a given string within a lower- and upper-bound gap of a second sub-string
edited title
Apr
14
comment Counting the number of instances of one sub-string within a given string within a lower- and upper-bound gap of a second sub-string
So string2 is special in the sense that if the values of string1 and string2 are exchanged, the resulting value of the count may be different?
Apr
14
revised How to produce functions
edited tags
Apr
14
comment Counting the number of instances of one sub-string within a given string within a lower- and upper-bound gap of a second sub-string
The problem may be clear in your mind, but I find it completely confusing. What has string1 and string2 to do with your example code? How does bigString come into play? You never mention it your text description of the problem.
Apr
14
reviewed Reviewed Counting the number of instances of one sub-string within a given string within a lower- and upper-bound gap of a second sub-string
Apr
14
comment How to change the appearance of a group opener?
@Sylvia. On OS X a group opener is a right facing triangle. I think it is stored in /Applications/Mathematica.app/Contents/Resources/RightArrow.icns, and I think one would have to change that icon file to change the appearance of a group opener. However, I am too timid to try the experiment on my system, so I don't know for sure.
Apr
14
revised Minimize solution to linear system with singular system matrix
Improved formatting
Apr
14
answered Unable to configure a system of differential equations
Apr
14
revised DSolve failing to solve second-order ODE with two boundary conditons
edited title
Apr
14
comment DSolve failing to solve second-order ODE with two boundary conditons
One possibility is that somewhere in your earlier session x was assigned a value, so your equation was no longer the symbolic expression you thought it was.
Apr
14
comment DSolve failing to solve second-order ODE with two boundary conditons
The easiest way -- if you are new to Mathematica -- is to save your notebook and restart Mathematica and reload the notebook. Or -- if you are feeling more adventurous, you can select Quit Kernel > Local from the Evaluation menu.
Apr
14
revised DSolve failing to solve second-order ODE with two boundary conditons
Improved formatting
Apr
14
comment DSolve failing to solve second-order ODE with two boundary conditons
I agree with @b.gatessucks. Your code worked fine on my system.
Apr
14
reviewed Approve suggested edit on How to manually set z-axis values in a 3d plot?
Apr
14
revised How to change the appearance of a group opener?
edited title