Hello there ,

I need to modify this code in MPI to calculate the value of Pie which is 3.14

/* File: mpi_trap1.c * Purpose: Use MPI to implement a parallel version of the trapezoidal * rule. In this version the endpoints of the interval and * the number of trapezoids are hardwired. * * Input: None. * Output: Estimate of the integral from a to b of f(x) * using the trapezoidal rule and n trapezoids. * * Compile: mpicc -g -Wall -o mpi_trap1 mpi_trap1.c -lm * Run: mpiexec -n ./mpi_trap1 * * Algorithm: * 1. Each process calculates "its" interval of * integration. * 2. Each process estimates the integral of f(x) * over its interval using the trapezoidal rule. * 3a. Each process != 0 sends its integral to 0. * 3b. Process 0 sums the calculations received from * the individual processes and prints the result. * * Note: f(x), a, b, and n are all hardwired. * * IPP: Section 3.2.2 (pp. 96 and ff.) */ #include

/* We'll be using MPI routines, definitions, etc. */ #include #include #include

/* Calculate local integral */ double Trap(double left_endpt, double right_endpt, int trap_count, double base_len);

/* Function we're integrating */ double f(double x);

int main(void) { int my_rank, comm_sz, n = 100000, local_n; double a = 0, b = 0, h, local_a, local_b; double local_int, total_int; int source; clock_t clockStart, clockEnd;

clockStart = clock();

/* Let the system do what it needs to start up MPI */ MPI_Init(NULL, NULL);

/* Get my process rank */ MPI_Comm_rank(MPI_COMM_WORLD, &my_rank);

/* Find out how many processes are being used */ MPI_Comm_size(MPI_COMM_WORLD, &comm_sz);

h = (b-a)/n; /* h is the same for all processes */ local_n = n/comm_sz; /* So is the number of trapezoids */

/* Length of each process' interval of * integration = local_n*h. So my interval * starts at: */ local_a = a + my_rank*local_n*h; local_b = local_a + local_n*h; local_int = Trap(local_a, local_b, local_n, h);

/* Add up the integrals calculated by each process */ if (my_rank != 0) { MPI_Send(&local_int, 1, MPI_DOUBLE, 0, 0, MPI_COMM_WORLD); } else { total_int = local_int; for (source = 1; source < comm_sz; source++) { MPI_Recv(&local_int, 1, MPI_DOUBLE, source, 0, MPI_COMM_WORLD, MPI_STATUS_IGNORE); total_int += local_int; } }

/* Print the result */ if (my_rank == 0) { clockEnd = clock(); printf("Time for MPI in parallel %3.5f seconds, estimate %.15e ", (clockEnd - clockStart) / (float)CLOCKS_PER_SEC, total_int); }

/* Shut down MPI */ MPI_Finalize();

if (my_rank == 0) { //Serial One double estimate = 0, x = 0; double left_endpt = a; double right_endpt = b; clockStart = clock();

estimate = (f(left_endpt) + f(right_endpt)) / 2.0; int i = 1; for (i = 1; i <= n - 1; i++) { x = a + i*h; estimate += f(x); } estimate = estimate*h;

clockEnd = clock(); printf("Time for MPI in serial %3.5f seconds, estimate %.15e ", (clockEnd - clockStart) / (float)CLOCKS_PER_SEC, estimate); } return 0; } /* main */

/*------------------------------------------------------------------ * Function: Trap * Purpose: Serial function for estimating a definite integral * using the trapezoidal rule * Input args: left_endpt * right_endpt * trap_count * base_len * Return val: Trapezoidal rule estimate of integral from * left_endpt to right_endpt using trap_count * trapezoids */ double Trap( double left_endpt /* in */, double right_endpt /* in */, int trap_count /* in */, double base_len /* in */) { double estimate, x; int i;

estimate = (f(left_endpt) + f(right_endpt))/2.0; for (i = 1; i <= trap_count-1; i++) { x = left_endpt + i*base_len; estimate += f(x); } estimate = estimate*base_len;

return estimate; } /* Trap */

/*------------------------------------------------------------------ * Function: f * Purpose: Compute value of function to be integrated * Input args: x */ double f(double x) { return sqrt(x*x*x); } /* f */

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extra information about Pie calculation in C# to add it to MPI code.

long num_steps = 100000; double h, y, area=0; h = 1.0 / (double)num_steps; for (int i = 0; i < num_steps; i++) { y = Math.Sqrt(1 - (i * h) * (i * h)); area = area + y * h; } pi = 4 * area;

thank you