I'm having some issues trying to install GSL for my programming course at uni (the course is taught in C). I'm using Visual Studio express 2012.
I've downloaded and run a precompiled GSL thing (GnuWin32) and changed my Linker and Includes options in VS, and the code is actually running properly. I've been using the following code as an example:
#include <math.h>
#include <stdio.h>
#include <gsl/gsl_matrix.h>
#include <gsl/gsl_blas.h>
int main()
{
size_t i,j;
gsl_matrix *m;
m = gsl_matrix_alloc (10, 10);
for (i = 0; i < 10; i++)
{
for (j = 0; j < 10; j++)
{
gsl_matrix_set (m, i, j, sin (i) + cos (j));
}
}
for (j = 0; j < 10; j++)
{
gsl_vector_view column = gsl_matrix_column (m, j);
double d;
d = gsl_blas_dnrm2 (&column.vector);
printf ("matrix column %d, norm = %g\n", j, d);
}
gsl_matrix_free(m);
}
This is running properly and giving me the correct output. However, when VS gets to the final curly bracket, it freaks out and gives me this error message:
"Run-Time Check Failure #0 - The value of ESP was not properly saved across a function call. This is usually a result of calling a function declared with one calling convention with a function pointer declared with a different calling convention."
Does anyone have an idea how to stop this happening? I've scoured the internet, and haven't found anything useful that I can understand.
'ESP was not saved properly' sounds like the standard asm code to save ESP into EBP failed or was not generated. There is a compiler option 'Omit frame pointers'. Check how it is set in your build for both the library and your main code. They both must be built the same way. Also, if you want a debugger to work, then uncheck this option.
Related
Here is my code that I am having issues with. The goal of the program is to scan in a bunch of doubles and perform some simple statistical operations on them. The line I am having the issue with is the fgets(). I have included the stdio.h, it's just not showing up in the code. My actual question is where are the stdin and NULL giving me issues when I though they were part of the language? The exact error I am getting is that both Symbol stdin and NULL could not be resolved.
/*
* simpleStats.c
*
* Created on: Sep 17, 2018
* Author: David Liotta
*/
#include <stdio.h>
#define BUFSIZE 256
int main(){
double n, max, min, sum, mean;
char line[BUFSIZE];
int numsRead = 0;
int numOfItems = 1;
n = -1;
max = n;
min = n;
sum = n;
while(n != 0 && fgets(line, BUFSIZE, stdin ) != NULL){
numsRead = sscanf(line, "%f", &n);
if(numsRead == 1 && n != 0){
numOfItems++;
if(n > max)
max = n;
if(n < min)
min = n;
sum = sum + n;
}
if(numsRead == 0)
printf("Bad input\n");
}
mean = sum / numOfItems;
printf("# of items: %i", numOfItems);
printf("\nSum: %f.3", sum);
printf("\nMax: %f.3", max);
printf("\nMin: %f.3", min);
printf("\nMean: %f.3", mean);
}
This code should compile. I suspect something might be wrong with your development environment.
Since you're running Eclipse, I'm assuming that your compiler is GCC. I may be wrong though.
Try to locate your compiler executable, and run the compilation by hand:
gcc -Wall -o simpleStats simpleStats.c
or, if you're on Windows:
gcc.exe -Wall -o simpleStats.exe simpleStats.c
You may have to specify the full path to gcc.exe, (depending on your environment, it might even be called something else; you may be able to retrieve the full path from the console window in Eclipse).
Pay close attention to the output. Copy/paste the full output verbatim in your original post if you can (do not rephrase the warnings / error messages).
I seldom use Eclipse, but with most IDEs you get to chose what kind of project you want to create. Make sure you selected something like "console application", the error you're referring to (stdin not being resolved) may suggest a linker error. Again, it's hard to tell without the exact GCC output.
A couple more things to check:
make sure your compiler and its dependencies are properly installed,
make sure that this compiler is targeted at Windows (or whatever OS you use), not at some exotic embedded platform,
most development environments come with a bunch of sample projects, see if you can build one.
The problem I was having ended up being the compiler not correctly reading the code. I used a different compiler, and with some minor syntax changes, the code worked fine.
How can you use some function written in C from R level using R data.
eg. to use function like:
double* addOneToVector(int n, const double* vector) {
double* ans = malloc(sizeof(double)*n);
for (int i = 0; i < n; ++i)
ans[i] = vector[i] + 1
return ans;
}
in the context:
x = 1:3
x = addOneToVector(x)
x # 2, 3, 4
I've searched stackoverflow first but I noticed there is no answer for that in here.
The general idea is (commands for linux, but same idea under other OS):
Create function that will only take pointers to basic types and do everything by side-effects (returns void). eg in a file called foo.c:
void addOneToVector(int* n, double* vector) {
for (int i = 0; i < *n; ++i)
vector[i] += 1.0;
}
Compile file C source as dynamic library, you can use R shortcut to do this:
$ R CMD SHLIB foo.c
This will then create a file called foo.so on Mac or foo.dll on Windows.
Load dynamic library from R
on Mac:
dyn.load("foo.so")
or on Windows:
dyn.load("foo.dll")
Call C functions using .C R function, IE:
x = 1:3
ret_val = .C("addOneToVector", n=length(x), vector=as.double(x))
It returns list from which you can get value of inputs after calling functions eg.
ret_val$x # 2, 3, 4
You can now wrap it to be able to use it from R easier.
There is a nice page describing whole process with more details here (also covering Fortran):
http://users.stat.umn.edu/~geyer/rc/
I just did the same thing in a very simple way using the Rcpp package. It allows you to write C++ functions directly in R.
library("Rcpp")
cppFunction("
NumericVector addOneToVector(NumericVector vector) {
int n = vector.size();
for (int i = 0; i < n; ++i)
vector[i] = vector[i] + 1.0;
return vector;
}")
Find more details here http://adv-r.had.co.nz/Rcpp.html. C++ functions can be done very fast with these instructions.
First off, I wanted to thank both #m0nhawk and #Jan for their immensely useful contributions to this problem.
I tried both methods on my MacBook: first the one showed m0nhawk which requires creating a function in C (without the main method) and then compiling using R CMD SHLIB <prog.c> and then invoking the function from R using the .C command
Here's a small C code I wrote (not a pro in C - just learning in bits and pieces)
Step 1: Write the C Program
#include <stdio.h>
int func_test() {
for(int i = 0; i < 5; i++) {
printf("The value of i is: %d\n", i);
}
return 0;
}
Step 2: Compile the program using
R CMD SHLIB func_test.c
This will produce a func_test.so file
Step 3: Now write the R Code that invokes this C function from within R Studio
dyn.load("/users/my_home_dir/xxx/ccode/ac.so")
.C("func_test")
Step 4: Output:
.C("func_test") The value of i is: 0 The value of i is: 1 The value of i is: 2 The value of i is: 3 The value of i is: 4 list()
Then I tried the direct method suggested by Jan - using the RCpp package
library("Rcpp")
cppFunction("
NumericVector addOneToVector(NumericVector vector) {
int n = vector.size();
for (int i = 0; i < n; ++i)
vector[i] = vector[i] + 1.0;
return vector;
}")
# Test code to test the function
addOneToVector(c(1,2,3))
Both methods worked superbly. I can now start writing functions in C or C++ and use them in R
Thank you once again!
My Thermo professor assigned our class a computational project in which we have to calculate some thermodynamic functions. He provided us with some code to work off of which is a program that essentially finds the area under a curve between two points for the function x^2. The code is said to be correct and it looks correct to me. However, I've been having FREQUENT problems with all of my programs giving me the error "'File location'.exe is not recognized as internal or external command, operable programs or batch files." upon initial running of a project or [mostly] reopening projects.
I've been researching the problem for many hours. I tried adjusting the environmental variables like so many other sites suggested, but I'm either not doing it right or it's not working. All I keep reading about is people explaining the purpose of an .exe file and that I have to locate that file and open that. The problem is that I cannot find ANY .exe file. There is the project I created with the source.c file I created and wrote the program in. Everything else has lengthy extensions that I've never seen before.
I'm growing increasingly impatient with Visual Studios' inconsistent behavior lately. I've just made the switch from MATLAB, which although is an inferior programming language, is far more user friendly and easier to program with. For those of you interested in the code I'm running, it is below:
#include <stdio.h>
#include <iostream>
#include <math.h>
using namespace std;
double integration();
double integration()
{
int num_of_intervals = 4, i;
double final_sum = 0, lower_limit = 2, upper_limit = 3, var, y = 1, x;
x = (upper_limit - lower_limit) / num_of_intervals; // Calculating delta x value
if(num_of_intervals % 2 != 0) //Simpson's rule can be performed only on even number of intervals
{
printf("Cannot perform integration. Number of intervals should be even");
return 0;
}
for(i = 0 ; i < num_of_intervals ; i++)
{
if(i != 0) //Coefficients for even and odd places. Even places, it is 2 and for odd it is 4.
{
if(i % 2 == 0)
y = 2;
else
y = 4;
}
var = lower_limit + (i * x);// Calculating the function variable value
final_sum = final_sum + (pow(var, 2) * y); //Calculating the sum
}
final_sum = (final_sum + pow(upper_limit , 2)) * x / 3; //Final sum
return final_sum;
}
int main()
{
printf("The integral value of x2 between limits 2 and 3 is %lf \n" , integration());
system("PAUSE");
return 0;
}
Thanks in advance,
Dom
I am following an example from CUNY and I have never done anything with C before so I probably don't know what I am doing.
Consider the program below.
Do I need a shebang line for C code written in emacs?
When I go to compile using the line gcc -g -o forwardadding forwardadding.c
I am hit with the message:
forwardadding.c:9:17: error: expected expression before ‘<’ token
Once I get the code compiles, I can use gdb to debug and run the code corrrect?
The code:
#include <stdio.h>
#include <math.h>
main()
{
float sum, term;
int i;
sum = 0.0;
for( i = 1; < 10000000; i++)
{
term = (float) i;
term = term * term;
term = 1 / term;
sum += term;
}
printf("The sum is %.12f\n", sum);
}
No shebang is needed. You could add an Emacs mode line comment.
The for loop should be:
for (i = 1; i < 10000000; i++)
Your code is missing the second i.
Yes, you can use GDB once you've got the code compiling.
You'd get a better answer to the mathematics if you counted down from 10,000,000 than by counting up to 10,000,000. After about i = 10000, the extra values add nothing to the result.
Please get into the habit of writing C99 code. That means you should write:
int main(void)
with the return type of int being required and the void being recommended.
You need to put a variable in the for loop for a complete expression (which is probably line 9...)
for( i = 1; < 10000000; i++)
change to this
for( i = 1; i < 10000000; i++)
You are missing an an i. Just correct that as Jonathan Leffler has suggested and save your file. Open your terminal and just use this to compile your code gcc your_file_name.c and your code compiles next to run the code that just compiled type ./a.out and your program runs and shows you the output.
I'm taking a class on C, and running into a segmentation fault. From what I understand, seg faults are supposed to occur when you're accessing memory that hasn't been allocated, or otherwise outside the bounds. 'Course all I'm trying to do is initialize an array (though rather large at that)
Am I simply misunderstanding how to parse a 2d array? Misplacing a bound is exactly what would cause a seg fault-- am I wrong in using a nested for-loop for this?
The professor provided the clock functions, so I'm hoping that's not the problem. I'm running this code in Cygwin, could that be the problem? Source code follows. Using c99 standard as well.
To be perfectly clear: I am looking for help understanding (and eventually fixing) the reason my code produces a seg fault.
#include <stdio.h>
#include <time.h>
int main(void){
//first define the array and two doubles to count elapsed seconds.
double rowMajor, colMajor;
rowMajor = colMajor = 0;
int majorArray [1000][1000] = {};
clock_t start, end;
//set it up to perform the test 100 times.
for(int k = 0; k<10; k++)
{
start=clock();
//first we do row major
for(int i = 0; i < 1000; i++)
{
for(int j = 0; j<1000; j++)
{
majorArray[i][j] = 314;
}
}
end=clock();
rowMajor+= (end-start)/(double)CLOCKS_PER_SEC;
//at this point, we've only done rowMajor, so elapsed = rowMajor
start=clock();
//now we do column major
for(int i = 0; i < 1000; i++)
{
for(int j = 0; j<1000; j++)
{
majorArray[j][i] = 314;
}
}
end=clock();
colMajor += (end-start)/(double)CLOCKS_PER_SEC;
}
//now that we've done the calculations 100 times, we can compare the values.
printf("Row major took %f seconds\n", rowMajor);
printf("Column major took %f seconds\n", colMajor);
if(rowMajor<colMajor)
{
printf("Row major is faster\n");
}
else
{
printf("Column major is faster\n");
}
return 0;
}
Your program works correctly on my computer (x86-64/Linux) so I suspect you're running into a system-specific limit on the size of the call stack. I don't know how much stack you get on Cygwin, but your array is 4,000,000 bytes (with 32-bit int) - that could easily be too big.
Try moving the declaration of majorArray out of main (put it right after the #includes) -- then it will be a global variable, which comes from a different allocation pool that can be much bigger.
By the way, this comparison is backwards:
if(rowMajor>colMajor)
{
printf("Row major is faster\n");
}
else
{
printf("Column major is faster\n");
}
Also, to do a test like this you really ought to repeat the process for many different array sizes and shapes.
You are trying to grab 1000 * 1000 * sizeof( int ) bytes on the stack. This is more then your OS allows for the stack growth. If on any Unix - check the ulimit -a for max stack size of the process.
As a rule of thumb - allocate big structures on the heap with malloc(3). Or use static arrays - outside of scope of any function.
In this case, you can replace the declaration of majorArray with:
int (*majorArray)[1000] = calloc(1000, sizeof majorArray);
I was unable to find any error in your code, so I compiled it and run it and worked as expected.
You have, however, a semantic error in your code:
start=clock();
//set it up to perform the test 100 times.
for(int k = 0; k<10; k++)
{
Should be:
//set it up to perform the test 100 times.
for(int k = 0; k<10; k++)
{
start=clock();
Also, the condition at the end should be changed to its inverse:
if(rowMajor<colMajor)
Finally, to avoid the problem of the os-specific stack size others mentioned, you should define your matrix outside main():
#include <stdio.h>
#include <time.h>
int majorArray [1000][1000];
int main(void){
//first define the array and two doubles to count elapsed seconds.
double rowMajor, colMajor;
rowMajor = colMajor = 0;
This code runs fine for me under Linux and I can't see anything obviously wrong about it. You can try to debug it via gdb. Compile it like this:
gcc -g -o testcode test.c
and then say
gdb ./testcode
and in gdb say run
If it crashes, say where and gdb tells you, where the crash occurred. Then you now in which line the error is.
The program is working perfectly when compiled by gcc, & run in Linux, Cygwin may very well be your problem here.
If it runs correctly elsewhere, you're most likely trying to grab more stack space than the OS allows. You're allocating 4MB on the stack (1 mill integers), which is way too much for allocating "safely" on the stack. malloc() and free() are your best bets here.