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SF bug 115831 and Ping's SF patch 101751, 0.0**-2.0 returns inf rather than

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raise ValueError.  Checked in the patch as far as it went, but also changed
all of ints, longs and floats to raise ZeroDivisionError instead when raising
0 to a negative number.  This is what 754-inspired stds require, as the "true
result" is an infinity obtained from finite operands, i.e. it's a singularity.
Also changed float pow to not be so timid about using its square-and-multiply
algorithm.  Note that what math.pow does is unrelated to what builtin pow
does, and will still vary by platform.
This commit is contained in:
Tim Peters 2000-10-06 00:36:09 +00:00
parent 4779a0a6fd
commit c54d19043a
4 changed files with 102 additions and 62 deletions
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85
Lib/test/test_pow.py
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@ -2,44 +2,69 @@ import sys
import test_support
def powtest(type):
if (type!=float):
if type != float:
print " Testing 2-argument pow() function..."
for i in range(-1000, 1000):
if (pow(type(i),0)!=1):
if pow(type(i), 0) != 1:
raise ValueError, 'pow('+str(i)+',0) != 1'
if (pow(type(i),1)!=type(i)):
if pow(type(i), 1) != type(i):
raise ValueError, 'pow('+str(i)+',1) != '+str(i)
if (pow(type(0),1)!=type(0)):
if pow(type(0), 1) != type(0):
raise ValueError, 'pow(0,'+str(i)+') != 0'
if (pow(type(1),1)!=type(1)):
if pow(type(1), 1) != type(1):
raise ValueError, 'pow(1,'+str(i)+') != 1'
for i in range(-100, 100):
if (pow(type(i),3)!=i*i*i):
if pow(type(i), 3) != i*i*i:
raise ValueError, 'pow('+str(i)+',3) != '+str(i*i*i)
pow2=1
pow2 = 1
for i in range(0,31):
if (pow(2,i)!=pow2):
if pow(2, i) != pow2:
raise ValueError, 'pow(2,'+str(i)+') != '+str(pow2)
if (i!=30): pow2=pow2*2
if i != 30 : pow2 = pow2*2
for othertype in int, long:
for i in range(-10, 0) + range(1, 10):
ii = type(i)
for j in range(1, 11):
jj = -othertype(j)
try:
pow(ii, jj)
except ValueError:
pass # taking an int to a neg int power should fail
else:
raise ValueError, "pow(%s, %s) did not fail" % (ii, jj)
for othertype in int, long, float:
for i in range(1, 100):
zero = type(0)
exp = -othertype(i/10.0)
if exp == 0:
continue
try:
pow(zero, exp)
except ZeroDivisionError:
pass # taking zero to any negative exponent should fail
else:
raise ValueError, "pow(%s, %s) did not fail" % (zero, exp)
print " Testing 3-argument pow() function..."
il, ih = -20, 20
jl, jh = -5, 5
kl, kh = -10, 10
compare = cmp
if (type==float):
il=1
if type == float:
il = 1
compare = test_support.fcmp
elif (type==int):
jl=0
elif (type==long):
jl,jh = 0, 15
elif type == int:
jl = 0
elif type == long:
jl, jh = 0, 15
for i in range(il, ih+1):
for j in range(jl,jh+1):
for j in range(jl, jh+1):
for k in range(kl, kh+1):
if (k!=0):
if k != 0:
if compare(pow(type(i),j,k), pow(type(i),j)% type(k)):
raise ValueError, "pow(" +str(i)+ "," +str(j)+ \
"," +str(k)+ ") != pow(" +str(i)+ "," + \
@ -81,15 +106,15 @@ print
for i in range(-10, 11):
for j in range(0, 6):
for k in range(-7, 11):
if (j>=0 and k!=0):
o=pow(i,j) % k
n=pow(i,j,k)
if (o!=n): print 'Integer mismatch:', i,j,k
if (j>=0 and k<>0):
o=pow(long(i),j) % k
n=pow(long(i),j,k)
if (o!=n): print 'Long mismatch:', i,j,k
if (i>=0 and k<>0):
o=pow(float(i),j) % k
n=pow(float(i),j,k)
if (o!=n): print 'Float mismatch:', i,j,k
if j >= 0 and k != 0:
o = pow(i,j) % k
n = pow(i,j,k)
if o != n: print 'Integer mismatch:', i,j,k
if j >= 0 and k <> 0:
o = pow(long(i),j) % k
n = pow(long(i),j,k)
if o != n: print 'Long mismatch:', i,j,k
if i >= 0 and k <> 0:
o = pow(float(i),j) % k
n = pow(float(i),j,k)
if o != n: print 'Float mismatch:', i,j,k