Hello, I'd first of all replace <pre>mpz_init_set_ui (exp, 1); by <pre>mpz_set_ui (exp, 1);</pre>and redo the timing test (you already mpz_init-ed exp - and you will only mpz_clear it once) </pre>CU, JDO <div> <blockquote style="border-left: 2px solid rgb(16, 16, 255); margin-left: 5px; padding-left: 5px;">----- Original Message ----- From: "Nustenil Segundo" <nustenilsegundo@gmail.com> To: gmp-discuss@swox.com Subject: GMP compared to JAVA Date: Thu, 20 Dec 2007 20:37:54 -0300 Hi, I did a aplication with GMP and other same in JAVA. This aplication calculates the value of the operation a^b mod m, for a, b and m randomical numbers of n bits, n in interval [5, 25000). The code in C (using GMP): #include <gmp.h> #include <stdio.h> #include <stdlib.h> #include <time.h> int main() { //DeclaraÃ§Ã£o de variÃ¡veis mpz_t op1, op2, mod, x, aux, exp; gmp_randstate_t state; unsigned long int n = 4, seed, i, j; clock_t ini, fim, temp; FILE *p; srand(time(NULL)); //inicializaÃ§Ã£o das variÃ¡veis do tipo GMP mpz_init(op2); mpz_init(x); mpz_init(op1); mpz_init(mod); mpz_init(aux); mpz_init(exp); gmp_randinit_default(state); //abre o arquivo "arquivo.txt" para escrita p = fopen("arquivomassa.txt", "w"); //laÃ§o para medir os bits e o tempo for(i=5 ; i<25000; i+=10){ mpz_init_set_ui (exp, 1); seed= rand(); gmp_randseed_ui (state,seed); //laÃ§o para o cÃ¡lculo de 2^exp for(j=1; j<=i; j++){ mpz_mul_ui(exp, exp, 2); } mpz_urandomb(aux, state, i); //aux Ã(c) um nÃºmero aleatÃ³rio de 0 a 2^i-1 mpz_add (op1, aux, exp); //op1 Ã(c) um nÃºmero de (i+1) bits mpz_urandomb(aux, state, i); //aux Ã(c) um nÃºmero aleatÃ³rio de 0 a 2^i-1 mpz_add (op2, aux, exp); //op2 Ã(c) um nÃºmero de (i+1) bits mpz_urandomb(aux, state, i); //aux Ã(c) um nÃºmero aleatÃ³rio de 0 a 2^i-1 mpz_add (mod, aux, exp); //mod Ã(c) um nÃºmero de (i+1) bits //calcula o tempo de [((op1)^(p2)) mod (mod)] e armazena em temp ini = clock(); mpz_powm (x, op1, op2, mod); fim = clock(); temp = fim - ini; printf("%lu\n", 1000*(unsigned long) temp/CLOCKS_PER_SEC); //armazena em arquivo.txt a quantidade de bits e o tempo da operaÃ§Ã£o fprintf(p, "%lu\t%lu\n", i+1, 1000*(unsigned long)temp/CLOCKS_PER_SEC); } gmp_randclear (state); mpz_clear (op1); mpz_clear (op2); mpz_clear (mod); mpz_clear (x); mpz_clear (aux); mpz_clear (exp); return 0; } The code in JAVA: import java.io.IOException ; import java.io.RandomAccessFile; import java.math.BigDecimal; import java.math.BigInteger; import java.util.Calendar; public class Big { /** * @param args * @throws IOException */ public static void main(String[] args) throws IOException { // String saida = ""; BigDecimal aux = new BigDecimal("16"); // BigDecimal condicaoParada = new BigDecimal("10").pow(1000); long cont = 5; String fimDeLinha = System.getProperty(" line.separator"); RandomAccessFile arquivo = new RandomAccessFile("tabela.txt","rw"); while(cont < 25000){ BigDecimal aleatorio = (new BigDecimal( Math.random()).multiply(aux)).add(aux); BigInteger p = new BigInteger(aleatorio.toString().substring(0, aleatorio.toString ().indexOf("."))); aleatorio = (new BigDecimal(Math.random()).multiply(aux)).add(aux); BigInteger q = new BigInteger(aleatorio.toString().substring(0, aleatorio.toString().indexOf("."))); aleatorio = (new BigDecimal(Math.random()).multiply(aux)).add(aux); BigInteger m = new BigInteger( aleatorio.toString().substring(0, aleatorio.toString().indexOf("."))); // saida += ; String saida = cont+" \t"+calculaTempo(p, q, m)+fimDeLinha; arquivo.seek (arquivo.length()); arquivo.write(saida.getBytes()); System.out.print(saida); cont+=10; aux = aux.multiply(new BigDecimal("1024")); } // System.out.println(saida); } private static long calculaTempo(BigInteger p, BigInteger q, BigInteger m) { long tempoInicial = Calendar.getInstance().getTimeInMillis(); BigInteger calculo = p.modPow(q, m); // BigInteger calculo = powBigInteger(p, q).mod(m); // q. long tempoFinal = Calendar.getInstance().getTimeInMillis(); // System.out.println("------ "+calculo); return tempoFinal - tempoInicial; } } For the result in C with n = 10005 bits the time was 2800 ms (a example). For the result in JAVA with n = 10005 bits the time was 10 ms (a example). Why this difference? Thanks, Nustenil Segundo de Moraes Lima Marinus _______________________________________________ gmp-discuss mailing list gmp-discuss@swox.com https://gmplib.org/mailman/listinfo/gmp-discuss </time.h></stdlib.h></stdio.h></gmp.h></nustenilsegundo@gmail.com></blockquote> </div> -- <div> Got No Time? Shop Online for <a href=http://mail.shopping.com/?linkin_id=8033174 target="_blank"> Great Gift Ideas!</a> mail.com Shopping</div>