C code

MATLAB code

// declare a double precision variable

// then assign a value

double a;

a = 5.0;

% variables are not declared and are

% double precision by default

a = 5.0;

// repeat which assigns values to

// array elements

for(i=1; i<=10; i++)

  A[i] = i;

% i = start:increment:end

% where increment = 1 is default

for i=1:10

    A(i) = i;

end

// repeat which prints a series of

// values

for(i=0; i<=10; i += 2)

  printf("%i \n", i);

for i=0:2:10

    fprintf(' %i \n', i)

end

// initialize identity matrix

enum(N=100);

double B[N];

for(r=0;r<N;r++)

  for(c=0;c<N;c++)

    B[r][c] = 0.0;

for(r=0;r<N;r++)

    B[r][r] = 1.0;

% MATLAB has functions for

% common array initializations

B = eye(100);

// declare and initialize an array

double C[3] = {1,2,3};

C = [1 2 3]; % or C = [1, 2, 3]

// declare and initialize an array

double C[4] = {2,4,6,8};

% array name = [start:increment:end];

C = [2:2:8];

// print an array element on screen

printf("%g \n", C[2]);

C(2) % no ending ; displays value

// declare and initialize an array

// with fixed interval between values

double C[4] = {2,4,6,8};

C = linspace(2,8,4)

% third param is optional and = # points

% between and including 1st two points

% if third param left off, default

% is 100 points

// declare and initialize a 2D array

enum{Rows=3, Cols=3};

double D[Rows][Cols] = {{1,2,3},

                        {4,5,6},

                        {7,8,9}};

% these three examples accomplish the

% same thing

D = [1 2 3; 4 5 6; 7 8 9];

D = [1:3; 4:6; 7:9];

D = [1 2 3

     4 5 6

     7 8 9];

// print element of 2D array

printf("%g \n", D[2][2]);

D(2,2) % row 2, column 2

// print selected sub array of 2D array

for(r=1; r<=2; r++)

  printf("%g \n", D[r][1]);

D(1:2,1) % rows 1 to 2 of column 1

// print all rows of column 1 of 2D

// array

for(r=1; r<Rows; r++)

  printf("%g \n", D[r][1]);

D(:,1) % all rows of column 1

// logical expression

double a = 1;

double b = 2;

if (a == 1 || b == 3)

  printf("a = 1 or b = 3 \n");

a = 1;

b = 2;

if a == 1 || b == 3

    fprintf('a = 2 or b = 3 \n');

end

// logical expresssion

if a == 1 && b != 3 {

    printf("a=1 and b not 3 \n");

    printf("OK? \n");

}

if a == 1 && b ~= 3

    fprintf('a=1 and b not 3 \n');

    fprintf('OK?');

end

// if structure

if a != 1

    fprintf('a is not 1 \n');

else if b != 3

    fprintf('b is not 3 \n');

else

    fprintf('huh? \n');

if a ~= 1

    fprintf('a is not 1 \n')

elseif b ~= 3

    fprintf('b is not 3 \n')

else

    fprintf('huh? \n')

end

// switch structure

switch a+b {

    case 1:

        printf("a+b = 1 \n");

        break;

    case 2:

        printf("a+b = 2 \n");

        break;

    case 3:

        printf("a+b = 3 \n");

        break;

    default:

        printf("a+b > 3 \n");

}

switch a+b

    case 1

        fprintf('a+b = 1 \n')

    case 2

        fprintf('a+b = 2 \n')

    case 3

        fprintf('a+b = 3 \n')

    otherwise

        fprintf('a+b > 3 \n')

end

// program which calls a function

#include <stdio.h>

% variables defined outside a

% program unit are global

y = 1;

z = 2;

main(){

  int b;

  b = myfunc(3);

  printf("%i \n", b);

}

// function definition can be in

// same file or separate file

int myfunc(int x){

  int a;

  a = x*y*z;

  return(a);

}

% program and function definition must

% be in separate files and function file

% must have same name as function

global y z

% declare global variables before

% first use

y = 1;

z = 2;

b = myfunc(3)

% function definition of myfunc

% must be in a separate file named

% myfunc.m (i.e., functionName.m)

LISTING OF FILE myfunc.m

function a = myfunc(x)

% function keyword, return variable

%               = function name (inputs)

%

% 1st continuous group of

% comments in a function are

% displayed when you enter 'help'

% and name of function in the command

% window

global y z

% declare global variables used

% in this file

a = x*y*z;

% return last value of return

% variable in file

% MATLAB functions can return an

% array

// matrix multiplication

// C = A*B

// where A is I rows by J columns

// B is J rows by K columns

// and C is I rows by K columns

// initialize matrix C so can

// accumulate

for(i=0; i<I; i++)

  for(k=0; k<K; k++)

    C[i][k] = 0;

// matrix multiplication, C = AB

for(k=0; k<K; k++)

  for(i=0; i<I; i++)

    for(j=0; j<J; j++)

      C[i][k] += A[i][j] * B[j][k];

C = A*B;