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Parallel Colt is a multithreaded version of Colt - a library for high performance scientific computing in Java. It contains efficient algorithms for data analysis, linear algebra, multi-dimensional arrays, Fourier transforms, statistics and histogramming.

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/*
Copyright (C) 1999 CERN - European Organization for Nuclear Research.
Permission to use, copy, modify, distribute and sell this software and its documentation for any purpose 
is hereby granted without fee, provided that the above copyright notice appear in all copies and 
that both that copyright notice and this permission notice appear in supporting documentation. 
CERN makes no representations about the suitability of this software for any purpose. 
It is provided "as is" without expressed or implied warranty.
 */
package cern.jet.random.tdouble;

/**
 * Not yet commented.
 */
class Stack {
    int N; /* max number of elts on stack */

    int[] v; /* array of values on the stack */

    int i; /* index of top of stack */

    /**
     * Constructs a new stack with the given capacity.
     */
    public Stack(int capacity) {
        this.N = capacity;
        this.i = -1; // indicates stack is empty
        this.v = new int[N];
        /*
         * static stack_t * new_stack(int N) { stack_t *s; s = (stack_t
         * *)malloc(sizeof(stack_t)); s->N = N; s->i = -1; // indicates stack is
         * empty s->v = (int *)malloc(sizeof(int)*N); return s; } static void
         * push_stack(stack_t *s, int v) { s->i += 1; if ((s->i) >= (s->N)) {
         * fprintf(stderr,"Cannot push stack!\n"); exit(0); // fatal!! }
         * (s->v)[s->i] = v; } static int pop_stack(stack_t *s) { if ((s->i) <
         * 0) { fprintf(stderr,"Cannot pop stack!\n"); exit(0); } s->i -= 1;
         * return ((s->v)[s->i + 1]); } static inline int size_stack(const
         * stack_t *s) { return s->i + 1; } static void free_stack(stack_t *s) {
         * free((char *)(s->v)); free((char *)s); }
         */
    }

    /**
     * Returns the topmost element.
     */
    public int pop() {
        if (this.i < 0)
            throw new InternalError("Cannot pop stack!");
        this.i--;
        return this.v[this.i + 1];
    }

    /**
     * Places the given value on top of the stack.
     */
    public void push(int value) {
        this.i++;
        if (this.i >= this.N)
            throw new InternalError("Cannot push stack!");
        this.v[this.i] = value;
    }

    /**
     * Returns the number of elements contained.
     */
    public int size() {
        return i + 1;
    }
}