Dimension an array with BigInteger?

Hi,
I'm wondering if it is possible to dimension an HUGE array with BigInteger..
my idea is if it is possible to the equivalent of e.g.
boolean b[] = new boolean[new BigInteger("12345678987654322346567")];Thanks!

No. The number in [] must be of type int (or promoted to int):
See: http://java.sun.com/docs/books/jls/second_edition/html/expressions.doc.html#46168
"The type of each dimension expression within a DimExpr must be an integral type, or a compile-time error occurs. Each expression undergoes unary numeric promotion (�5.6.1). The promoted type must be int, or a compile-time error occurs; this means, specifically, that the type of a dimension expression must not be long."

Similar Messages

Auto-indexing is slow for arrays with 1 dimensions

Hi,
I was looking at the performance of operations on all individual elements in 3D arrays, especially the difference between auto-indexing (left image) and manual-indexing (right image, calling "Index array" and "Replace array subset" in the innermost loop). I'm a bit puzzled by the results and post it here for discussion and hopefully somebody's benefit in the future.
Left: auto-indexing; right: manual-indexing
In the tests I added a different random number to all individual elements in a 3D array. I found that auto-indexing is 1.2 to 1.5 times slower than manual-indexing. I also found that the performance of auto-indexing is much more dependent on the size the dimensions: an array with 1000x200x40 elements is 20% slower than an array with 1000x40x200 elements. For manual-indexing there is hardly any difference. The detailed results can be found at the end of this post.
I was under the impression that auto-indexing was the preferred method for this kind of operation: it achieves exactly the same result and it is much clearer in the block diagram. I also expected that auto-indexing would have been optimized in LabView, but the the tests show this is clearly not the case.
What is auto-indexing doing?
With two tests I looked at how auto-index works.
First, I looked if auto-indexing reorganizes the data in an inefficient way. To do this I made a method "fake-auto-indexing" which calls "Array subset" and "Reshape array" (or "Index array" for a 1D-array) when it enters _every_ loop and calls "Replace array subset" when exiting _every_ loop (as opposed to manual-indexing, where I do this only in the inner loop). I replicated this in a test (calling it fake-auto-indexing) and found that the performance is very similar to auto-indexing, especially looking at the trend for the different array lengths.
Fake-auto-indexing
Second, I looked if Locality of reference (how the 3D array is stored in memory and how efficiently you can iterate over that) may be an issue. Auto-indexing loops over pages-rows-columns (i.e. pages in the outer for-loop, rows in the middle for-loop, columns in the inner for-loop). This can't be changed for auto-indexing, but I did change it for manual and fake-indexing. The performance of manual-indexing is now similar to auto-indexing, except for two cases that I can't explain. Fake-auto-indexing performs way worse in all cases.
It seems that the performance problem with auto-indexing is due to inefficient data organization.
Other tests
I did the same tests for 1D and 2D arrays. For 1D arrays the three methods perform identical. For 2D arrays auto-indexing is 15% slower than manual-indexing, while fake-auto-indexing is 8% slower than manual-indexing. I find it interesting that auto-indexing is the slowest of the three methods.
Finally, I tested the performance of operating on entire columns (instead of every single element) of a 3D array. In all cases it is a lot faster than iterating over individual elements. Auto-indexing is more than 1.8 to 3.4 times slower than manual-indexing, while fake-auto-indexing is about 1.5 to 2.7 times slower. Because of the number of iterations that has to be done, the effect of the size of the column is important: an array with 1000x200x40 elements is in all cases much slower than an array with 1000x40x200 elements.
Discussion & conclusions
In all the cases I tested, auto-indexing is significantly slower than manual-indexing. Because auto-indexing is the standard way of indexing arrays in LabView I expected the method to be highly optimized. Judging by the tests I did, that is not the case. I find this puzzling.
Does anybody know any best practices when it comes to working with >1D arrays? It seems there is a lack of documentation about the performance, surprising given the significant differences I found.
It is of course possible that I made mistakes. I tried to keep the code as straightforward as possible to minimize that risk. Still, I hope somebody can double-check the work I did.
Results
I ran the tests on a computer with a i5-4570 @ 3.20 GHz processor (4 cores, but only 1 is used), 8 GB RAM running Windows 7 64-bit and LabView 2013 32-bit. The tests were averaged 10 times. The results are in milliseconds.
3D-arrays, iterate pages-rows-columns
pages x rows x cols : auto    manual fake
   40 x 200 x 1000 : 268.9   202.0   268.8
   40 x 1000 x 200 : 276.9   204.1   263.8
200 x   40 x 1000 : 264.6   202.8   260.6
200 x 1000 x   40 : 306.9   205.0   300.0
1000 x   40 x 200 : 253.7   203.1   259.3
1000 x 200 x   40 : 307.2   206.2   288.5
100 x 100 x 100 : 36.2    25.7    33.9
3D-arrays, iterate columns-rows-pages
pages x rows x cols : manual fake
   40 x 200 x 1000 : 277.6   457
   40 x 1000 x 200 : 291.6   461.5
200 x   40 x 1000 : 277.4   431.9
200 x 1000 x   40 : 452.5   572.1
1000 x   40 x 200 : 298.1   460.4
1000 x 200 x   40 : 460.5   583.8
100 x 100 x 100 : 31.7    51.9
2D-arrays, iterate rows-columns
rows x cols : auto     manual   fake
200 x 20000 : 123.5    106.1    113.2
20000 x   200 : 119.5    106.1    115.0
10000 x 10000 : 3080.25 2659.65 2835.1
1D-arrays, iterate over columns
cols   : auto manual fake
500000 : 11.5 11.8    11.6
3D-arrays, iterate pages-rows, operate on columns
pages x rows x cols : auto    manual fake
   40 x 200 x 1000 : 83.9   23.3     62.9
   40 x 1000 x 200 : 89.6   31.9     69.0
200 x   40 x 1000 : 74.3   27.6     62.2
200 x 1000 x   40 : 135.6   76.2    107.1
1000 x   40 x 200 : 75.3   31.2     68.6
1000 x 200 x   40 : 133.6   71.7    108.7
100 x 100 x 100 : 13.0    5.4      9.9
VI's
I attached the VI's I used for testing. "ND_add_random_number.vi" (where N is 1, 2 or 3) is where all the action happens, taking a selector with a method and an array with the N dimensions as input. It returns the result and time in milliseconds. Using "ND_add_random_number_automated_test.vi" I run this for a few different situations (auto/manual/fake-indexing, interchanging the dimensions). The VI's starting with "3D_locality_" are used for the locality tests. The VI's starting with "3D_norows_" are used for the iterations over pages and columns only.
Attachments:
3D_arrays_2.zip ‏222 KB

Robert,
the copy-thing is not specific for auto-indexing. It is common for all tunnels. A tunnel is first of all a unique data space.
This sounds hard, but there is an optimization in the compiler trying to reduce the number of copies the VI will create. This optimization is called "in-placeness".
The in-placeness algorithm checks, if the wire passing data to the is connected to anything else ("branch"). If there is no other connection then the tunnel, chance is high that the tunnel won't create an additional copy.
Speaking of loops, tunnels always copies. The in-placeness algorithm cannot opt that out.
You can do a small test to elaborate on this: Simply wire "0" (or anything less than the array sizy of the input array) to the 'N' terminal.......
Norbert
PS: Auto-indexing is perfect for a "by element" operation of analysis without modification of the element in the array. If you want to modify values, use shift registers and Replace Array Subset.
CEO: What exactly is stopping us from doing this?
Expert: Geometry
Marketing Manager: Just ignore it.

How to create a array with variables dimensions?

I try to create a array like that:
Object[][] data;
data = new Object[] [];
But that's doesn't work!
Apparently I must specify the dimension of my array
So I have done like that :
Object[][] data;
data = new Object[3] [3];
And that work!
But the problem is when I need to add extra elements to my array.
If I write :
data[4][1] = "123";
I have the error message :
java.lang.ArrayIndexOutOfBoundsException
So, how can I defined a array with variables dimensions OR how can I add a dimension to a array?

if you have:
Object[][] data;
data = new Object[3] [3];you end yo getting ArrayIndexOutOfBoundException if you try to point to some other Indexes. You can increase the size by doing new:
Object[][] data;
data = new Object[4] [3];and then copy the old Arrays to this one... this is heavy.
Other thing to consider then is using some other datastructure, such as Vector, which grows along you add elements to it.
P_trg

Multi-dimensional arrays with non-specified dimension

Hi all,
I'm trying to write a method to create a multi-dimensional array of
Integer, based on another one, taken as parameter. I would like the
method to work for an array of a non-specified dimension, that is,
it could take as parameter a Integer[], or a Integer[][], or a
Integer[][][] and so on.
The idea is to have as a result an array with the original elements
doubled.
Here is my recursive function:
    public static Object[] f(Object[] a) {
         // the array to be returned is created with the
         // same size as the original
        Object[] r = new Object[a.length];
        for (int i=0; i<a.length; i++) {
            Object elem = a;
Object newElem = null;
if (elem instanceof Object[]) {
// Recursive case
newElem = f((Object[]) elem);
} else if (elem instanceof Integer) {
// Base case
newElem = new Integer(((Integer)elem).intValue() * 2);
r[i] = newElem;
return r;
This method returns an array with the same structure (that is, same
dimensions) of the array taken in the constructor. In the recursive
case, it just calls the function to the inner arrays. In the base
case, where I have an Integer, it creates a new Integer, whose
value is the old multiplied by 2.
Then I initialize an array:
    public static void main(String args[]) throws Exception {
        Integer[][] a = new Integer[][] {
            new Integer[] {
                new Integer(0), new Integer(2)
            new Integer[] {
                new Integer(1), new Integer(4), new Integer(3)
// And try to call the function like this:
        Integer [][] b = (Integer [][]) f(a);
    }   And I get a java.lang.ClassCastException: [Ljava.lang.Object;
I don't understand the reason of this exception, because the
object returned is a Integer[][]. Isn't it?
And since I don't have a compiler error in the cast, that means
that Object[] and Integer[][] are not inconvertible. Right?
Could anyone explain me why this is wrong and/or give me some
ideas to do what I'm trying to do?
Thanks a lot,
Angela

I retract my previous statement about using
reflection. Use "Object[] r =(Object[])a.clone()"
to create a new array of the same type.You don't need temporary array variable here.
You could simply use argument a instead of r.
(But this my gotcha is derived from your clever rep.)Well, this isn't a temporary variable, its the return variable, which is different. If you don't want the original matrix changed, you have to clone the argument.

Lots of blank space when printing array with only last element printed

I have a slight problem I have been trying to figure it out for days but can't see where my problem is, its probably staring me in the face but just can't seem to see it.
I am trying to print out my 2 dimensional array outdie my try block. Inside the trying block I have two for loops in for the arrays. Within the second for loop I have a while to put token from Stringtokeniser into my 2 arrays. When I print my arrays in this while bit it prints fine however when I print outside the try block it only print the last element and lots of blank space before the element.
Below is the code, hope you guys can see the problem. Thank you in advance
   import java.io.*;
   import java.net.*;
   import java.lang.*;
   import java.util.*;
   import javax.swing.*;
   public class javaflights4
      public static final String MESSAGE_SEPERATOR = "#";
      public static final String MESSAGE_SEPERATOR1 = "*";
      public static void main(String[] args) throws IOException
         String data = null;
         File file;
         BufferedReader reader = null;
         file = new File("datafile.txt");
         String flights[] [];
               //String flightdata[];
         flights = new String[21][7];
         int x = 0;
               //flightdata = new String[7];
         int y = 0;
         try
            reader = new BufferedReader(new FileReader(file));
            //data = reader.readLine();
            while((data = reader.readLine())!= null)
               data.trim();
               StringTokenizer tokenised = new StringTokenizer(data, MESSAGE_SEPERATOR1);
               for(x = 0; x<=flights.length; x++)
                  for(y = 0; y<=flights.length; y++)
                     while(tokenised.hasMoreTokens())
                        //System.out.println(tokenised.nextToken());
                        flights [x] [y] = tokenised.nextToken();
                        //System.out.print("*"+ flights [x] [y]+"&");
               System.out.println();
            catch(ArrayIndexOutOfBoundsException e1)
               System.out.println("error at " + e1);
            catch(Exception e)
            finally
               try
                  reader.close();
                  catch(Exception e)
         int i = 0;
         int j = 0;
         System.out.print(flights [j]);
//System.out.println();

A number of problems.
First, I bet you see a lot of "error at" messages, don't you? You create a 21x7 array, then go through the first array up to 21, going through the second one all the way to 21 as well.
your second for loop should go to flights[x].length, not flights.length. That will eliminate the need for ArrayIndexOutOfBounds checking, which should have been an indication that you were doing something wrong.
Second, when you get to flights[0][0] (the very first iteration of the inner loop) you are taking every element from the StringTokenizer and setting flights[0][0] to each, thereby overwriting the previous one. There will be nothing in the StringTokenizer left for any of the other (21x7)-1=146 array elements. At the end of all the loops, the very first element in the array (flights[0][0]) should contain the last token in the file.
At the end, you only print the first element (i=0, j=0, println(flight[ i][j])) which explains why you see the last element from the file.
I'm assuming you have a file with 21 lines, each of which has 7 items on the line. Here is some pseudo-code to help you out:
count the lines
reset the file
create a 2d array with the first dimension set to the number of lines.
int i = 0;
while (read a line) {
Tokenize the line;
count the tokens;
create an array whose size is the number of tokens;
stuff the tokens into the array;
set flights[i++] to this array;
}

How to fill array with random number?

I need to fill a 3-dimensional array that has user-controlled dimension sizes with random numbers (1-10). I'm unsure of how to do this. I feel like I have to use the initialize array and maybe the build array functions somehow but I'm not entirely sure. Any help would be appreciated. Thanks.

Something like this
Kudos are always welcome if you got solution to some extent.
I need my difficulties because they are necessary to enjoy my success.
--Ranjeet
Attachments:
Array with random number.vi ‏9 KB

Multi-dimensional array with dynamic size - how to?

Hi
I have a CONSTANT number of buckets. Each of them has to take a VARIOUS number of data series. The data series have one VARIOUS length per bucket. I'd like to index the buckets like an array to loop over them.
So basically I need something like a multidimensional array with constant first dimension (bucket index), but dynamic second (data series index within bucket) and third (data point index within data series) dimension. What's the best way to do so?
I should also remark that data series can get really big.
Thanks in advance and best regards,
Michael

Hi Michael,
the usual way is to use an array of cluster.
Put your "2nd" and "3rd" data into a cluster and then make an 1D array of that cluster...
Best regards,
GerdW
CLAD, using 2009SP1 + LV2011SP1 + LV2014SP1 on WinXP+Win7+cRIO
Kudos are welcome

Regarding Dimensions of Array

Hi ..well i am just wondering wht is the limit to Dimension of Array in Java. my ultimate goal is to handle large matrices.
Looking forward for your response..thanking u ..!!

Hmmm... that question could be interpreted in at least two ways.
1. How many dimensions can an array type have? I believe the answer is around 255.
2. How many levels of arrays can be stored in any array? This is limited only by available memory.
Remember that "multidimensional arrays" are really just arrays of arrays, and that arrays are objects. Thus, you could have an array of objects whose elements are actually arrays:
Object[] deep = new Object[10];
deep[0] = new Object[10];
((Object[]) deep[0])[0] = new Object[10];
((Object[]) ((Object[]) deep[0])[0])[0] = new Object[10];
// etc.Actually, an element of an array can be a reference to the array itself:
Object[] recursive = new Object[1];
recursive[0] = recursive;so in a sense that is a "bottomless" array!
If you're willing to code the array accesses with lots of casts, you can handle any number of dimensions, and even arrays of "ragged" dimension.

Problem with BigInteger and MySql

Hi !!
I've a problem with BigInteger and MySql.
I've a BigInteger object (suppose that value is 0.02270412445068359375).
I must store that value in a database (MySql).
The value of BigInteger object must be stored in a column of type Decimal.
Stored value is 0.022704124450683594. Why ??
My target is to store 0.02270412445068359375
Can anyone help me?
Thanks.

Hi !!
I've a problem with BigInteger and MySql.
I've a BigInteger object (suppose that value is
0.02270412445068359375).
I must store that value in a database (MySql).
The value of BigInteger object must be stored in a
column of type Decimal.if this is the case I fear you are SOL. a decimal is the same size as a double but with a fixed max number of decimal places. if it isn't big enough then you have no real choice other than to VARCHAR it.
Stored value is 0.022704124450683594. Why ??
My target is to store 0.02270412445068359375
Can anyone help me?
Thanks.

Unable to plot 1-D array with a cluster of 2 elements on an XY graph

I'm Unable to plot a 1-D array with a cluster of 2 elements on an XY graph. The data appears at the input to the graph but nothing is plotted. I'm trying to plot a line connecting each point generated.
Solved!
Go to Solution.
Attachments:
TEST11.vi ‏13 KB

Chuck,
0. Do not post VIs with infinite loops! Change the True constant to a control. One of the regular participants on these Forums has commented that using the Abort button to stop a VI is like using a tree to stop a car. It works, but may have undesired consequences!
1. Use a shift register on the For loop also.
2. Inserting into an empty array leaves you with an empty array. Initialize the array outside the loop to a size greater or equal to the maximum size you will be using. Then use Replace Array Subest inside the loop.
3. Just make an array of the cluster of points. No need for the extra cluster.
Lynn
Attachments:
TEST11.2.vi ‏11 KB

I have read 118 files (from a directory) each with 2088 data and put them into a 2 D array with 2cols and 246384row, I want to have aeach file on a separate columns with 2088 rows

I have read 118 files from a directory using the list.vi. Each file has 2 cols with 2088rows. Now I have the data in a 2 D array with 2cols and 246384rows (118files * 2088rows). However I want to put each file in the same array but each file in separate columns. then I would have 236 columns (2cols for each of the 118 files) by 2088 rows. thank you very much in advance.

Hiya,
here's a couple of .vi's that might help out. I've taken a minimum manipulation approach by using replace array subset, and I'm not bothering to strip out the 1D array before inserting it. Instead I flip the array of filenames, and from this fill in the end 2-D array from the right, overwriting the column that will eventually become the "X" data values (same for each file) and appear on the right.
The second .vi is a sub.vi I posted elsewhere on the discussion group to get the number of lines in a file. If you're sure that you know the number of data points is always going to be 2088, then replace this sub vi with a constant to speed up the program. (by about 2 seconds!)
I've also updated the .vi to work as a sub.vi if you wa
nt it to, complete with error handling.
Hope this helps.
S.
// it takes almost no time to rate an answer
Attachments:
read_files_updated.vi ‏81 KB
Num_Lines_in_File.vi ‏62 KB

Populating a javascript array with datatable data

I want to populate a javascript array with datatable data.
How do I do this?
I want the javascript array to be populated as the datatable is displayed.
Doing this way doesn't work.
<h:dataTable value="#{pmManager.profiles}" var="pmProfile" binding="#{pmManagerUiBean.uiTable}" ">
<script>
allProfilenames[index]='#{pmProfile.profileName}';
          alert("index ="+index);
          alert("...1"+allProfilenames[0]);
          alert("...2"+allProfileRes[0]);
          index++;
</script>
<h:dataTable>

In Javascript do something like this:
document.getElementById('form1:dec_param');
where form1:dec_param is the id of the component on the page source (html)

How to build a array with collected data

Hi,
I have collected data from serial port with VISA. Now I want to build a array with 100 date points. Should I connect VISA Read with Build Array directly? How to do it?
PS: All of them are in a While Structure.
Thank you!

An inefficient way to create the array is to use the build array and a shift register as shown below. It's more effecient in terms of memory management to create the array and then use the replace array subset as shown in the other image. Of course, if you don't need the array inside the loop, just wire the value out of the while loop and on the exit tunnel, right click and select 'Enable Indexing'.
Message Edited by Dennis Knutson on 07-03-2007 10:25 PM
Message Edited by Dennis Knutson on 07-03-2007 10:26 PM
Attachments:
Crude Build Array.PNG ‏4 KB
Better Build Array.PNG ‏6 KB

How to build a array with high sampling rates 1K

Hi All:
Now I am trying to develop a project with CRio.
But I am not sure how to build a array with high sampling rates signal, like >1K. (Sigle-point data)
Before, I would like to use "Build Arrary" and "Shift Register" to build a arrary, but I found it is not working for high sampling rates.
Is there anyother good way to build a data arrary for high sampling rates??
Thanks
Attachments:
Building_Array_high_rates.JPG ‏120 KB

Can't give a sample of the FPGA right now but here is a sample bit of RT code I recently used. I am acquiring data at 51,200 samples every second. I put the data in a FIFO on the FPGA side, then I read from that FIFO on the RT side and insert the data into a pre-initialized array using "Replace Array subset" NOT "Insert into array". I keep a count of the data I have read/inserted, and once I am at 51,200 samples, I know I have 1 full second of data. At this point, I add it to a queue which sends it to another loop to be processed. Also, I don't use the new index terminal in my subVI because I know I am always adding 6400 elements so I can just multiply my counter by 6400, but if you use the method described further down below , you will want to use the "new index" to return a value because you may not always read the same number of elements using that method.
The reason I use a timeout of 0 and a wait until next ms multiple is because if you use a timeout wired to the FIFO read node, it spins a loop in the background that polls for data, which rails your processor. Depending on what type of acquisition you are doing, you can also use the method of reading 0 elements, then using the "elements remaining" variable, to wire up another node as is shown below. This was not an option for me because of my programs architecture and needing chunks of 1 second data. Had I used this method it would have overcomplicated things if I read more elements then I had available in my 51,200 buffer.
Let me knwo if you have more qeustions
CLA, LabVIEW Versions 2010-2013
Attachments:
RT.PNG ‏36 KB
FIFO read.PNG ‏4 KB

Possible bug: Saving array with extended and double precision to spreadsheet

If one concatenates a double precision array and an extended precision array with the "build array" vi and then saves using "Write to Spreadsheet File" vi any digits to the right of the decimal place are set to zero in the saved file. This happens regardless of the format signifier input (e.g. %.10f) to the "Write to Spreadsheet File" vi.
I am on Vista Ultimate 32 bit and labview 9.0
This is a possible bug that is easily circumvented by converting to one type before combining arrar to a spreadsheet. Nonetheless, it is a bug and it cost me some time.
Solved!
Go to Solution.
Attachments:
Spreadsheet save bug.vi ‏9 KB

Hi JL,
no, it's not a bug - it's a feature
Well, if you would look more closely you would recognize the "Save to Spreadsheet" as polymorphic VI. As this polymorphic VI doesn't support EXT numbers internally (it only supports DBL, I64 and String) LabVIEW chooses the instance with most accuracy: I64 (I64 has 64 bits precision, DBL only 53...). So your options are:
- set the instance to use as DBL (by right-click and "Select type...")
- make a copy of this VI, save it with a different name and make it support EXT numbers (don't rework the polymorphic VI as you would break compatibility with other LV installations or future revisions)
And yes, those coercion dots always signal some conversions - you should atleast check what's going on there...
Message Edited by GerdW on 05-21-2010 10:01 PM
Best regards,
GerdW
CLAD, using 2009SP1 + LV2011SP1 + LV2014SP1 on WinXP+Win7+cRIO
Kudos are welcome

Dimension an array with BigInteger?

Similar Messages

Maybe you are looking for