Moved weave

1 files changed, 143 insertions, 0 deletions

diff --git a/scipy/weave/examples/fibonacci.py b/scipy/weave/examples/fibonacci.py
new file mode 100644
index 000000000..3905ccd04
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+++ b/scipy/weave/examples/fibonacci.py
@@ -0,0 +1,143 @@
+# Typical run:
+# C:\home\eric\wrk\scipy\weave\examples>python fibonacci.py
+# Recursively computing the first 30 fibonacci numbers:
+#  speed in python: 4.31599998474
+#  speed in c: 0.0499999523163
+#  speed up: 86.32
+# Looping to compute the first 30 fibonacci numbers:
+#  speed in python: 0.000520999908447
+#  speed in c: 5.00000715256e-005
+#  speed up: 10.42
+# fib(30) 832040 832040 832040 832040
+
+import sys
+sys.path.insert(0,'..')
+import ext_tools
+
+def build_fibonacci():
+    """ Builds an extension module with fibonacci calculators.
+    """
+    mod = ext_tools.ext_module('fibonacci_ext')
+    a = 1 # this is effectively a type declaration
+    
+    # recursive fibonacci in C 
+    fib_code = """
+                   int fib1(int a)
+                   {                   
+                       if(a <= 2)
+                           return 1;
+                       else
+                           return fib1(a-2) + fib1(a-1);  
+                   }                         
+               """
+    ext_code = """
+                   return_val = fib1(a);
+               """    
+    fib = ext_tools.ext_function('c_fib1',ext_code,['a'])
+    fib.customize.add_support_code(fib_code)
+    mod.add_function(fib)
+
+    # looping fibonacci in C
+    fib_code = """
+                    int fib2( int a )
+                    {
+                        int last, next_to_last, result;
+            
+                        if( a <= 2 )
+                            return 1;            
+                        last = next_to_last = 1;
+                        for(int i = 2; i < a; i++ )
+                        {
+                            result = last + next_to_last;
+                            next_to_last = last;
+                            last = result;
+                        }
+            
+                        return result;
+                    }    
+               """
+    ext_code = """
+                   return_val = fib2(a);
+               """    
+    fib = ext_tools.ext_function('c_fib2',ext_code,['a'])
+    fib.customize.add_support_code(fib_code)
+    mod.add_function(fib)       
+    mod.compile()
+
+try:
+    import fibonacci_ext
+except ImportError:
+    build_fibonacci()
+    import fibonacci_ext
+c_fib1 = fibonacci_ext.c_fib1
+c_fib2 = fibonacci_ext.c_fib2
+
+#################################################################
+# This where it might normally end, but we've added some timings
+# below. Recursive solutions are much slower, and C is 10-50x faster
+# than equivalent in Python for this simple little routine
+#
+#################################################################
+
+def py_fib1(a):
+    if a <= 2:
+        return 1
+    else:
+        return py_fib1(a-2) + py_fib1(a-1)
+
+def py_fib2(a):
+    if a <= 2:
+        return 1            
+    last = next_to_last = 1
+    for i in range(2,a):
+        result = last + next_to_last
+        next_to_last = last
+        last = result
+    return result;
+
+import time
+
+def recurse_compare(n):
+    print 'Recursively computing the first %d fibonacci numbers:' % n
+    t1 = time.time()
+    for i in range(n):
+        py_fib1(i)
+    t2 = time.time()
+    py = t2- t1
+    print ' speed in python:', t2 - t1
+    
+    #load into cache
+    c_fib1(i)
+    t1 = time.time()
+    for i in range(n):
+        c_fib1(i)
+    t2 = time.time()    
+    print ' speed in c:',t2 - t1    
+    print ' speed up: %3.2f' % (py/(t2-t1))
+
+def loop_compare(m,n):
+    print 'Looping to compute the first %d fibonacci numbers:' % n
+    t1 = time.time()
+    for i in range(m):
+        for i in range(n):
+            py_fib2(i)
+    t2 = time.time()
+    py = (t2-t1)
+    print ' speed in python:', (t2 - t1)/m
+    
+    #load into cache
+    c_fib2(i)
+    t1 = time.time()
+    for i in range(m):
+        for i in range(n):
+            c_fib2(i)
+    t2 = time.time()
+    print ' speed in c:',(t2 - t1)/ m    
+    print ' speed up: %3.2f' % (py/(t2-t1))
+    
+if __name__ == "__main__":
+    n = 30
+    recurse_compare(n)
+    m= 1000    
+    loop_compare(m,n)    
+    print 'fib(30)', c_fib1(30),py_fib1(30),c_fib2(30),py_fib2(30)
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