把内容过程中经常用到的一些内容段做个备份，如下的内容是关于Evaluate X and Y returned from the differential equation solvers using printput frequency in Python的内容，应该是对码农们也有好处。
''' printSoln(X,Y,freq).
Prints X and Y returned from the differential
equation solvers using printput frequency 'freq'.
freq = n prints every nth step.
freq = 0 prints initial and final values only.
'''
def printSoln(X,Y,freq):
def printHead(n):
print "n x ",
for i in range (n):
print " y[",i,"] ",
print
def printLine(x,y,n):
print "%13.4e"% x,
for i in range (n):
print "%13.4e"% y[i],
print
m = len(Y)
try: n = len(Y[0])
except TypeError: n = 1
if freq == 0: freq = m
printHead(n)
for i in range(0,m,freq):
printLine(X[i],Y[i],n)
if i != m - 1: printLine(X[m - 1],Y[m - 1],n)