Physics Forums - Programming & Comp Sci

How to calculate arithmetic sum of multiple strings

Monique — Wed, 22 May 2013 10:01:03 GMT

I have a MySQL database and I have the problem that queries take way too much time. I want to optimize the database and one way would be to save data into a string, instead of in rows (the string would be replicates of the same condition).

Each string is an interval of 4 seconds, to reduce the number of rows further I want to sum the data into 30-minute intervals. How can I sum strings? I'd like to use PHP for that. Shall I push replicates into an array?

NULL values may be present

To illustrate:
time 1: 0,1,0,1,1,1,0
time 2: 1,1,0,,0,1,1

sum time 1+2: 1,2,0,1,1,2,1

Akima bivariate interpolation

DrClaude — Wed, 22 May 2013 09:10:14 GMT

Anyone familiar with the bivariate interpolation method developed by Akima?

I've been reading H. Akima, Commun. ACM 17, 18 (1974) and trying to implement his method, but he actually doesn't describe how to do the interpolation! The formulas for calculating the derivatives at each point are given, but not the polynomial that uses them for the interpolation.

I've been trying to reverse engineer his code, but it's starting to take too much of my time. Any help welcome.

Weird C++ Array Issue

Vorde — Tue, 21 May 2013 21:31:17 GMT

Hello all,

I'm not really a programmer at all, but I learned c++ for a while so I can do basic stuff. Having just finished my linear algebra class I suddenly had an urge to write myself a simple matrix solver. I knew it wouldn't be easy (especially because of my lack of skill) but I was curious.

It was going great until I noticed that large matrices would crash the program. It's very weird. If the number of entries in my matrix array is less than 10 then everything works fine, but the second it hits 10 it stops working. I get the following message:

Quote:

Windows has triggered a breakpoint in Matrix.exe.

This may be due to a corruption of the heap, which indicates a bug in Matrix.exe or any of the DLLs it has loaded.

I was hoping someone could help me figure out why in gods name this is happening. I apologize in advance for the messiness of my code, I haven't yet made it nice (I was going to once I got the matrix entry down), but I put in a couple of notes to try and help.

Thank you very much :)

Edit: Something I should add: it doesn't crash when I made the size > 10 entries, it crashes when I enter the value for the 10th entry.

Code:

// Matrix.cpp : main project file.



#include "stdafx.h"

#include 



int main()

{

    using namespace std;



        // definition of array values

        struct Entry

        {

                long double Value;

                int mVal;

                int nVal;

                bool pivot;

        };



        // beginning of program

        int mSize;

        int nSize;

        int tSize;

        Entry *toSize = new Entry[tSize]; // creating array

                cout << "Height of Matrix (M-Val):" << endl;

                cin >> mSize;

                cout << "Width of Matrix (N-Val):" << endl;

                cin >> nSize;

                tSize = (nSize * mSize);

        int B;

        int Num = 1;

        int modN = 1;

        int modM = 1;



                // entering values

                        while (B < tSize)

                        {

                                long double value;

                                cout << "What do you want entry " << "(" << modM << "," << modN << ")" << " to be?" << endl;

                                cin >> value;

                                toSize[B].Value = value;

                                        if (modN < nSize)

                                        {

                                                toSize[B].nVal = modN;

                                                toSize[B].mVal = modM;

                                        }



                                        else

                                        {

                                                toSize[B].nVal = modN;

                                                modN = 0;

                                                toSize[B].mVal = modM;

                                                modM ++;

                                        }        

                                B ++;

                                Num ++;

                                modN ++;

                        }

        int T;

        cout << "\n \n" << endl;

        // printing values and placements

                while (T < tSize)

                {

                        cout << "Value is:" << toSize[T].Value << endl;

                        cout << "M-Placement is:  " << toSize[T].mVal << endl;

                        cout << "N-Placement is:  " << toSize[T].nVal << endl;

                        cout << "\n" << endl;

                        T++;

                }



// so it doesn't close immediately

        cin.clear();

        cin.ignore(255, '\n');

        cin.get();

  

}

Problem setting integer precision in Fortran

GabDX — Sun, 19 May 2013 20:30:58 GMT

I'm trying to work with big integers but for some reason this program won't compile:

Code:

program prob003

   implicit none

   integer, parameter :: k32 = selected_int_kind(32)

   integer(kind=k32) :: num = 600851475143 

end program prob003

The file name is prob003.f90 and I'm trying to compile with gfortran without any option:

Code:

gfortran prob003.f90

I keep getting this error:

Code:

prob003.f90:3.42:



   integer(kind=k32) :: num = 600851475143 

                                          1

Error: Integer too big for its kind at (1). This check can be disabled with the option -fno-range-check

It does compile if I remove 3 digits from that number however. What am I doing wrong?

Nested Loops in Python (really stupid question)

cepheid — Thu, 16 May 2013 18:20:14 GMT

My code isn't working, and the reason seems to be because nested for loops in python don't work according to my expectations. If I have some code like this:

Code:



f1 = open('name_of_file1.txt', 'r')

f2 = open('name_of_file2.txt', 'r')



for line1 in f1:

    #stuff at this level should happen once for every line in file1. Right???

    print line1

    for line2 in f2:

            #stuff at this level should happen once for every line in file2. Right???

            print line2

My expectation for the output:

Code:



line 1 from file1

.

.

.

(all lines from file2 here)

.

.

.

line 2 from file1

.

.

.

(all lines from file2 here)

.

.

.

line 3 from file1

.

.

.

(all lines from file2 here)

.

.

.

et cetera

The output that I ACTUALLY get:

Code:

line 1 from file1

.

.

.

(all lines from file2 here)

.

.

.

(all remaining lines from file1 in sequence)

Huh???

Calculating digits of Grahams' Number

madmike159 — Thu, 16 May 2013 15:20:08 GMT

I was reading random topics on Wikipedia the other day, and saw something about the first 500 numbers of Grahams' Number.

I want to create a program (probably in C#) to calculate as many digits from it as I can, but I haven't be able to make sense of the way it is done. Would someone be able to give me a hint of how the algorithm works. The only examples I was able to find were written in Python, which I wasn't really able to get my head around.

How to read APIs (Python)(PyBrain)

K29 — Wed, 15 May 2013 19:24:50 GMT

I am having trouble getting the hang of understanding APIs. After going through tutorials I find myself wanting to see what parameters I can pass to an object. So I look in the api and I see stuff like *args and **kwargs

e.g.
http://pybrain.org/docs/api/structur...ForwardNetwork

I've looked everywhere to try and find what those *args consist of, but I'm at a loss. Anyone frequently consult API documentation and know what I should be reading?

G++ Shared Library Issues

PPeter — Wed, 15 May 2013 03:16:04 GMT

Before I switched to Opensuse 12.3, I was running Arch, and doing something like:

Code:

g++ -o test -I ./include/ -L ./lib/ -ltcod -ltcodxx ./src/main.cpp

with no problems occuring.

Now, when I try to do that (with everything kept the exact same as when on Arch), I get:

Code:

/usr/lib64/gcc/x86_64-suse-linux/4.7/../../../../x86_64-suse-linux/bin/ld: skipping incompatible lib/libtcod.so when searching for -ltcod

/usr/lib64/gcc/x86_64-suse-linux/4.7/../../../../x86_64-suse-linux/bin/ld: cannot find -ltcod

/usr/lib64/gcc/x86_64-suse-linux/4.7/../../../../x86_64-suse-linux/bin/ld: skipping incompatible lib/libtcodxx.so when searching for -ltcodxx

/usr/lib64/gcc/x86_64-suse-linux/4.7/../../../../x86_64-suse-linux/bin/ld: cannot find -ltcodxx

I also tried including -Wl,-rpath=./lib/ , but it still made no difference.

Any help as to why the libraries have become incompatible all of a sudden would be greatly appreciated.

Velocity from a data set

ShoxPhysics — Tue, 14 May 2013 07:23:03 GMT

I have just about finished this program, I only need to calculate my velocity. I think that this velocity should be calculated by taking the value from the 4th column of my data set here:https://docs.google.com/file/d/0BzuD...it?usp=sharing which have called ivar_3 and multiplying it by the difference of the 1st column in the line of the value and the line preceding it. Is this thought process correct? I have done the following (code I am talking about is in blue), can somebody tell me where I might be going wrong because it will not compile?

Code:

program WSUPhys_csv

  implicit none



  integer :: stat, num_lines, ivar1, ivar2, ivar3, &

             MaxVert,MaxSide,MaxForward

  real :: rvar, Sum_ivar1, Sum_ivar2, Sum_ivar3, & 

          Avg_ivar1, Avg_ivar2, Avg_ivar3, Vel, SumVel, MaxVel

  character*80 :: line

  logical :: err

  

  err = .false.



  write(*,*) "Reading file..."



  ! open input file

  open(10,file='DATA-002.csv',status='old',iostat=stat)

  if (stat .ne. 0) then

    err = .true.

    write(*,*) 'File cannot be opened !'

    go to 99   

  end if



  num_lines = 0

  Sum_ivar1 = 0

  Sum_ivar2 = 0

  Sum_ivar3 = 0

  MaxVert=0

  MaxSide=0

  MaxForward=0

  SumVel=0

  MaxVel=0

  do

    read(10,'(A)',end=99, iostat=stat) line 

    if (stat .ne. 0) then

      err = .true.

      write(*,*) 'Error reading data !'

      go to 99

    end if

    ! skip comment/header lines beginning with ";"

    if (adjustl(trim(line(1:1))) .eq. ';') then

      cycle

    end if

    ! read string line into numeric variables

    read(line,*) rvar, ivar1, ivar2, ivar3

    num_lines = num_lines + 1    

    if (num_lines <=  10) then

      write(*,*) num_lines, ':', rvar, ivar1, ivar2, ivar3

    end if

    Sum_ivar1 = Sum_ivar1 + ABS(ivar1) 

    Sum_ivar2 = Sum_ivar2 + ABS(ivar2) 

    Sum_ivar3 = Sum_ivar3 + ABS(ivar3)

    Vel=(ABS(ivar_3))*(rvar-rvar)

    SumVel=SumVel+ ABS(Vel)

    If (ABS(ivar1) > MaxVert) then

      MaxVert=ivar1

    end if

    If (ABS(ivar2) > MaxSide) then

      MaxSide=ivar1

    end if

    If (ABS(ivar3) > MaxForward) then

      MaxForward=ivar1

    end if   

    If (Vel > MaxVel) then

      MaxVel=Vel

  end do

  ! close file

  99 continue

  close (10)



  ! when file processing OK

  if (.not. err) then

    write(*,*) '...done.'

    ! compute averages

    Avg_ivar1 = (Sum_ivar1 / num_lines)

    Avg_ivar2 = (Sum_ivar2 / num_lines)

    Avg_ivar3 = (Sum_ivar3 / num_lines)

    AvgVel = (SumVel / num_lines)

    !



    write(*,*) 'Lines processed: ', num_lines

    write(*,*) 'Average vertical acceleration', Avg_ivar1

    write(*,*) 'Average sideways acceleration', Avg_ivar2

    write(*,*) 'Average forwards acceleration', Avg_ivar3

    write(*,*) 'Maximum vertical acceleration', MaxVert

    write(*,*) 'Maximum sideways acceleration', MaxSide

    write(*,*) 'Maximum forward acceleration ',  MaxForward

    write (*,*) 'Average forward velocity', AvgVel

    write (*,*) 'Maximum velocity', MaxVel

  end if  

end program WSUPhys_csv

Fortran 95 and HTML form

onlybarca6 — Mon, 13 May 2013 14:43:29 GMT

I've got a Fortran 95 program (which basically does few calculations) and I'd like to use it online. So that, the users will input data into a HTML form, the program will run, and it will display the results.

Would it be possible to do it in the following way?
To run a little program (e.g. PHP) once the user submits the form, then that program would take the input values from the form and write them into a text file.
Then it runs the Fortran program, which reads the input values from the text file and does all the calculations - outputting the results to another text file (and then back to the website).

If that's possible, how do I put all these steps into one thing, so that they'll be executed one after another?

Thank you very much for your help!

Using a self-coded neural network

roldy — Mon, 13 May 2013 06:47:27 GMT

I developed a multi-layer perceptron so I could better understand the underlying structure as well as modify it easily versus MATLAB's nntoolbox generate code. I have successfully trained the network for a given set of inputs and targets. The question now is how do I use this trained network with a new set of inputs? I've looked everywhere and I can't seem to find out what procedure I need to take. Would this involve using the weights of the trained network somehow?

Problem in Extracting Numercial Values in fortran

equillibrium — Sun, 12 May 2013 18:57:14 GMT

Hello all,I have a small doubt. I use F95/90 and IBM compiler.This is a portion of my text file
-----------------------
Alpha Singles Amplitudes
15 3 23 4 -0.186952
15 3 26 4 0.599918
15 3 31 4 0.105048
15 3 23 4 0.186952
Beta Singles Amplitudes
15 3 23 4 0.186952
15 3 26 4 -0.599918
15 3 31 4 -0.105048
15 3 23 4 -0.186952
END
---------------------
I am trying to extract the numerical values from the attached file 1.txt . and I am facing a strange error in the output which I cannot understand. Every time I execute the program it skips the loop between 'Beta' and 'END'. I am trying to read and store the values.
The number of lines inside the Alpha- and beta loop is not fixed. So a simple 'do loop' is of no use to me. I tried the 'do while' but it gives the output as :
-------------------------------------------------------------------------------------
AS 15 3 23 4 -.186952
AS 15 3 26 4 .599918
AS 15 3 31 4 .105048
AS 15 3 23 4 .186952
1525-097 A READ statement using decimal base input found the invalid digit 'a' in the input file. The program will recover by assuming a zero in its place.
1525-097 A READ statement using decimal base input found the invalid digit 'e' in the input file. The program will recover by assuming a zero in its place.
1525-097 A READ statement using decimal base input found the invalid digit 'p' in the input file. The program will recover by assuming a zero in its place.
1525-097 A READ statement using decimal base input found the invalid digit 'l' in the input file. The program will recover by assuming a zero in its place.
This is the end
--------------------------------------------------------------------------------------
Any suggestions would of of great help. I coudn't find the error in logic in my code.I have attached the code (Text.txt).

Thanks in advance

Attached Files

	1.txt (378 Bytes)
	Test.txt (1.3 KB)

Fortran- maximum values

ShoxPhysics — Sun, 12 May 2013 08:57:19 GMT

Hello I am currently working on a program that will take the values from a .csv file containing multiple data and analyzing them. The file can be found here: https://docs.google.com/file/d/0BzuD...it?usp=sharing The data in question starts in row 11 and is in the first 4 columns. In my program I have labeled these: rvar, ivar1, ivar2, ivar3. Rvar is the value corresponding to a time value in microseconds after start of recording whereas ivar1,ivar2,and ivar3 correspond to the value of the acceleration at that point. I have already calculated the average value of each of these columns.

My question is- how do I find the maximum value for ivar1, ivar2 and ivar3 (separately)?

My current code is below:

Code:

program WSUPhys_csv

  implicit none



  integer :: stat, num_lines, ivar1, ivar2, ivar3

  real :: rvar

  character*80 :: line

  

  write(*,*) "Reading file..."



  ! open input file

  open(10,file='DATA-002.csv',status='old',iostat=stat)

  if (stat .ne. 0) then

    write(*,*) 'File cannot be opened !'

    go to 99   

  end if



  num_lines = 0

  do

    read(10,'(A)',end=99, iostat=stat) line 

    if (stat .ne. 0) then

      write(*,*) 'Error reading data !'

      go to 99

    end if

    ! skip comment/header lines beginning with ";"

    if (adjustl(trim(line(1:1))) .eq. ';') then

      cycle

    end if

    ! read string line into numeric variables

    read(line,*) rvar, ivar1, ivar2, ivar3

    num_lines = num_lines + 1    

    if (num_lines <=  10) then

      write(*,*) num_lines, ':', rvar, ivar1, ivar2, ivar3

    end if

  Sum_ivar1 = Sum_ivar1 + ABS(ivar1) 

  Sum_ivar2 = Sum_ivar2 + ABS(ivar2) 

  Sum_ivar3 = Sum_ivar3 + ABS(ivar3)

  Max

  end do



  ! close file

  99 continue

  Avg_ivar1 = (Sum_ivar1 / num_lines)

  Avg_ivar2 = (Sum_ivar2 / num_lines)

  Avg_ivar3 = (Sum_ivar3 / num_lines)

  close (10)

  !

  write(*,*) '...done.'

  write(*,*) 'Lines processed: ', num_lines

  write(*,*) 'Average vertical acceleration', Avg_ivar1/1000

  write(*,*) 'Average sideways acceleration', Avg_ivar2/1000

  write(*,*) 'Average forward acceleration', Avg_ivar3/1000

end program WSUPhys_csv

Overlapping Matches Python

TylerH — Sat, 11 May 2013 06:08:22 GMT

I'm writing a function to take a string like "aXYb" and return a regex in which the lower case letters act like actual character and the upper case become free variables.

The regex generated from "aXYb" should match anything of the form a([a-z]+)([a-z]+)b. It does. But not exactly as "freely" as I would like. For example, when I re.compile(a([a-z]+)([a-z]+)b).match("aaxab"), the only tuple I get back is ("ax", "a").

Preferably, I'd like both ("a", "xa") and ("ax", "a"). How can I change "a([a-z]+)([a-z]+)b" to get these results?

For a little background, it's intended to be used in describing rules for algebraic manipulations (in the abstract algebra sense). The final goal is to be able do a breadth first search of all manipulations until I get to the desired result. The free variables are used in describing the variable part of valid manipulations, like (AB=AC -> B=C). That's why overlapping is absolutely necessary.

MIPS assembly progr.-factorial calculation

electra123 — Fri, 10 May 2013 21:00:45 GMT

I'm trying to write a MIPS assembly program that implements the calculation of n! Well i wouldn't be here if i were successful.When i try to run the following code on PCSpim this appears on the screen:
"Exception 6 [Bad instruction address] occured and ignored"
Can anyone help me find my errors?i think my head is going to explode!

Thanks in advance...

Here is my code:

Quote:

.data 0x10008000
.word 10
.word 1
.word 0
.ascii "The factorial of 10 is %d \n"
.text
.globl main

main:
addi $sp,$sp,-8
sw $ra,4($sp)
sw $fp,8($sp)
addiu $fp,$sp,4
lw $a0,4($gp)
jal fact

move $a1,$v0

jal printf
lw $ra,4($sp)
lw $fp,8($sp)
addi $sp,$sp,8
jr $ra

fact:
addi $sp,$sp,-8
sw $ra,4($sp)
sw $fp,8($sp)
addiu $fp,$sp,4
sw $a0,0($fp)

lw $v0,0($fp)

move $t0,$zero
slti $t0,$v0,1
beq $t0,$zero,L2
addi $v0,$zero,1
jr L1

L1:
lw $ra,4($sp)
lw $fp,8($sp)
addiu $sp,$sp,8
jr $ra

L2:
lw $v1,0($fp)
subu $v0,$v1,1
move $a0,$v0
jal fact
lw $v1,0($fp)
mul $v0,$v0,$v1

printf:
li $v0,4
la $a0,12($gp)
syscall

li $v0,1
move $a0,$v1
syscall