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--- gibson:teaching:fall-2014:math445:lecture9-diary [2014/10/13 19:51]
gibson [for loops]
+++ gibson:teaching:fall-2014:math445:lecture9-diary [2014/10/15 12:45] (current)
gibson [example: solving a nonlinear equation]
@@ Line 30: / Line 30: @@
 **example 3:** Write a ''mysum'' function that computes the sum of the elements of a vector.
+<code matlab>
+function s = mysum(x)
+% return the sum of the components of vector x
+  s = 0;               % start with partial sum s = 0
+  for i = 1:length(x)  % loop over all elements in x
+    s = s + x(i);      % add x(i) to the previously computed partial sum
+  end
+end
+</code>
 **example 4:** Write a function that computes the factorial of //n//.
+<code matlab>
+function p = factorial(n)
+% return the factorial of n (assume n is a positive integer)
+  p = 1;               % start with partial product p = 1
+  for k = 1:n          % loop k over all integers from 1 to n
+    p = p*k;           % multiply previous partial product by k
+  end
+end
+</code>
 **The for loop is probably the single most important programming construct in numerical mathematics.**
 ===== while loops =====
@@ Line 48: / Line 70: @@
 For example, the factorial function above could also be written this way...

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