Comments and Ratings

Missing function substr

I've been looking for something like this for a while! thanks!!!

Meows quite adequately.

Awesome. Quite awesome. I often have a lot of figures open for comparison and it's great to cycle through them easily. Thank you for a great submission.

If it is all about speed, remove the error checks! For larger numbers the following formula is more appropriate:
exp(gammaln(N+1) - gammaln(K+1) - gammaln(N-K+1)) ;

Why submit functions that do the same thing that existing utilities in MATLB do better?

nchoosek does the same computation, but does it better, since nchoosek offers more functionality, and already exists in every copy of matlab for as far back as I can recall.

This has little in the way of error checking. No H1 line.

Admittedly, if you are trying to compute large binomial coefficients, you will be far better off using a variety of other tools. But this one fails when it needs not do so.

>> nchoosek(1000,800)
Warning: Result may not be exact. Coefficient is greater than 1.000000e+15
 and is only accurate to 15 digits.
> In nchoosek at 66
ans =
     6.61715556065931e+215

>> choose(1000,800)
ans =
   NaN

See CELL2FLOAT
http://www.mathworks.com/matlabcentral/fileexchange/19730

for a more flexible implementation.

And who is the author of this submission? Vasi or Feldman?

Perhaps fig may be available on the internet, but where? Give a link. Is it really that difficult to be friendly to those who might try to download your work? Is it really necessary for others to be forced to do these searches to find out how to use your code?

IF your code uses something that will not be available in MATLAB proper, then tell people about it. If it uses a toolbox function, then show that toolbox as a dependency. If it uses another FEX submission, then tell people about it. Put a link in your code that shows where to find it. Do NOT post code that has dependencies without that information, as this then is non-working code. Non-working code is by definition poor.

After writing the comment I browesed the file exchange for a while and I ran into the fig function... Liked the fig function as well :) Any way, I find the colors.m helpful - it is always annoying to choose the colors by guessing...

Cute idea.
The code does not run unless:
 the cell2num command is changed to cell2mat
and
the fig commant is changed to figure, for example by the following 2 lines:
handle= figure(1);
set(handle,'Position',[100,100, 1000, 900])

unfortunately, this script does not run due to missing functions

- cell2num
- fig

us

I see that the code has been updated to provide vectorized operation. As always, I should consider raising my rating.

First, I looked for an H1 line. No. Still a blank line as the very first line of the help. This is utterly silly, since the second line of the help is a perfectly serviceable H1 line. This disables lookfor. Interestingly, the help facility that automatically builds a contents file for directories using the first lines of the help blocks finds roundl. But lookfor is itself disabled here. So this problem has not been repaired.

How bout the vectorized question?

x = rand(1,5)*100
x =
    74.555 73.627 56.186 18.419 59.721

roundl(x)
ans =
   100 100 50 20 50

By default, roundl uses a rounding strategy, i.e., a rounding mode of 'n'. But it can round up or down, more like a ceiling or floor operation then. All of these operations work nicely, and a default appears to be supplied for the rounding mode if necessary. Or is it?

roundl(x,'n')
ans =
   100 100 50 20 50

roundl(x,'u')
ans =
   100 100 100 20 100

roundl(x,'d')
ans =
    50 50 50 10 50

Now try the code by adding the third argument. The third argument to roundl allows you to control the levels rounded to.

roundl(x,'n',7)
ans =
    80 80 60 20 60

No problem so far. But what happens if you don't wish to change the default for the rounding mode, only the default for n? The paradigm in MATLAB when you have variables that will take on a default is if the variable is left empty ([]), then use the default. Does this work? No. This fails. I tried these things:

roundl(x,[],7)
??? Error using ==> roundl at 120
Invalid rounding mode:

roundl(x,'',7)
??? Error using ==> roundl at 120
Invalid rounding mode:

I even tried this:

roundl(x,7)
??? Error using ==> roundl at 120
Invalid rounding mode: 

As I said, this fails to follow the standard MATLAB paradigm for default arguments, which makes the code not very friendly. If you wish to change the rounding level, you must also provide a default for the other parameter. It is a truly silly flaw, because is it really that difficult to write your code as:

if (nargin < 2) || isempty(n), mode= 'n'; end

versus the line as it was written?

if nargin < 2, mode= 'n'; end

Sorry, but it is easy to write friendly code, and it is easy to make the code compatible with lookfor. Given this newly found problem, a 3 rating still applies here.

Despite the claim, this fails to run on all operating systems. Try it on a PPC Mac. No go.

unix('hostname') works fairly well if you are on a PPC mac. I've not verified it is correct for an intel mac.

I quite liked the basic idea when I saw it. However, there are a couple of flaws I found. The first was a surprise to me. It is not vectorized?

roundl(rand(20,1)*100)
??? Error using ==> mpower
Matrix must be square.

Error in ==> roundl at 91
   if (10^log10x_frac <= sqrt( multiplier(n,i-1)*multiplier(n,i) ) )

So this takes only scalar input? You are kidding me, right? A silly thing, IMHO. Since this is absolutely trivial to vectorize, why not do so?

The help was quite reasonable in general. It was missing an H1 line. Well, actually, it HAS an H1 line, but in the wrong place. There is a blank comment line as the very first line of the help. This causes problems for the lookfor function, since it looks at the very first comment line in the help block. Why do you want lookfor to work? Lookfor is the tool that your user will use next month or next year when they forget the name of your function. But by leaving that first line blank, you just disabled lookfor.

I did find error checks that seemed reasonable. Mlint points out a couple of minor items, like the use of | instead of || in conditionals. Read the help for relop to learn the difference.