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====== Differences ====== This shows you the differences between two versions of the page.

--- gibson:teaching:fall-2013:math445:lecture5functions [2013/09/10 12:54]
gibson created
+++ gibson:teaching:fall-2013:math445:lecture5functions [2013/09/10 13:05] (current)
gibson
@@ Line 1: / Line 1: @@
-The functions we wrote in class are provided below. Each has a description of what we're illustrating, the filename, and then the file contents. You can cut & paste as needed.
+The functions we wrote in class are provided below. Each lists the filename, a description of what we're illustrating, and then the file contents. You can cut & paste as needed.
-An example of an if-else statement.
-isOdd.m
+square.m : a super-simple example of a function that takes one argument and returns one value
+<code>
+function s = square(x);  % declare a function named square
+% square takes an argument x and returns its square, s=x*x
+  s = x*x;
+end
+</code>
+pow.m : an example of a function that takes two arguments
+<code>
+function y = pow(x,n) % this function takes two arguments
+% pow(x,n): return x to the n
+  y = x^n; % semicolon to suppress printing
+end
+</code>
+square_cube.m : an example of a function with two return values
+<code>
+function [s,c] = square_cube(x); % example of multiple return values
+% return the square and the cube of x
+  s = x*x;
+  c = s*x;
+end
+</code>
+isOdd.m : an example of an if-else statement
 <code>
 function r = isOdd(n)
@@ Line 16: / Line 50: @@
-A simpler example of an if-else statement
+isTwo.m : a simpler example of an if-else statement
-isTwo.m
 <code>
 function r = isTwo(n);
@@ Line 33: / Line 65: @@
 end
 </code>
+printtoten.m : a simple example of a for-loop, with no arguments and no return value
+<code>
+function printtoten();
+% print the numbers from 1 to 10
+  % example for loop
+  for n=1:10
+    n
+  end
+end
+</code>
+sumtoten.m : a more meaningful example of a for-loop
+<code>
+function s = sumtoten();
+% return the sum of 1 through 10
+  s = 0; % set s to zero
+  for n=1:10
+    s = s+n;   % add each number from 1 to 10 to s
+  end
+end
+</code>
+matvecmult.m : a home-grown matrix-vector multiply function
+<code>
+function y = matvecmult(A,x);
+% return y = A*x;
+  [m,n] = size(A);  % get size of matrix
+  y = zeros(m,1);
+  % Compute y(i) = sum A_ij x_j
+  % "nested loops"
+  for i=1:m
+    for j=1:n
+      y(i) = y(i) + A(i,j)*x(j);
+    end
+  end
+end
+</code>

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