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POHow to change heap and stack memory size in GCC 4.6.3?
 

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  1. POHow to change heap and stack memory size in GCC 4.6.3?
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    <p>While using malloc I have noticed that the pointer assigned is null. I want to allocate much more memory around 30 MB to the heap memory during execution of the code. How can I do so on Ubuntu 12.04 LTS with GCC 4.6.3 used as a compiler? Should I allocate more stack memory instead? Would it be better?</p> <p>Thanks</p> <p>Edit the problematic part of the code, the code is terminated after the if statement.</p> <pre><code>#include &lt;stdio.h&gt; #include &lt;math.h&gt; #include &lt;limits.h&gt; #include &lt;stdlib.h&gt; #define a0 0.53 #define N LONG_MAX // This value of N is the highest possible number in long double // data format over 100. Higher is not possible due to the size of // the default heap memory. Change its value to adjust the precision of // integration and computation time. Since exponential decays really fast // a modest value of N is enough for this integration. // The discrete integral may be defined as follows: long double trapezoid(long double x[],long double f[]) { int i; long double dx = x[1]-x[0]; long double sum = 0.5*(f[0]+f[N]); for (i = 1; i &lt; N; i++) sum+=f[i]; return sum*dx; } main() { printf("LONG_MAX constant has the following value: %ld \n", LONG_MAX); long double * P = malloc(N * sizeof(long double)); long double * r = malloc(N * sizeof(long double)); long double * PP = malloc(N * sizeof(long double)); // The if statement is to check if the memory allocation has // been done and terminate the program otherwise. if (P == 0 || r == 0) { printf("ERROR: Out of memory\n"); return 1; } // Declare and initialize the loop variable } </code></pre>
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    1. USVesnog
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      1. POHow to change heap and stack memory size in GCC 4.6.3?
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    1. COHeap is the way to go for big chunks of memory. I am able to allocate one gigabyte easily with `malloc`, so your problem is elsewhere. Are you working on a particularly limited platform?
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      1. POHow to change heap and stack memory size in GCC 4.6.3?
      1. USMagnus Hoff
    2. COIs your system configured to limit per process memory allocation? What is the output of `ulimit -v`?
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      1. POHow to change heap and stack memory size in GCC 4.6.3?
      1. USMagnus Hoff
    3. COAre you allocating in one big chunk, or are you making multiple smaller allocations? How many?
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      1. POHow to change heap and stack memory size in GCC 4.6.3?
      1. USMagnus Hoff
 

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