On 25 ene, 12:21, William Stein <wst...@gmail.com> wrote:
> That's bad, because z is zero after all. Yes, "bool(foo==bar)" being
> True means that Sage couldn't prove that foo == bar, but in this case,
> since z does equal z, and it isn't difficult to change Sage that it
> would know this, I don't see why we don't do it.
Glad to hear that my suggestion got liked.
Just in case it is useful, there go the "overlay" functions I wrote
for myself, which send every angle to the 1st quadrant, keeping track
of the signs:
# Thanks! Greetings,
# Jesús TC
def mycos(x) :
if x >= 0 and x <= pi/2 :
return cos(x)
else :
if x < 0 :
x = -x
while x >= 2*pi :
x = x - 2*pi
if x > pi/2 and x <= pi :
return -cos(pi-x)
elif x > pi and x <= 3*pi/2 :
return -cos(x-pi)
elif x > 3*pi/2 :
return cos(2*pi-x)
else :
return cos(x)
def mysin(x) :
if x >= 0 and x <= pi/2 :
return sin(x)
else :
f = +1
if x < 0 :
x = -x
f = -1
while x >= 2*pi :
x = x - 2*pi
if x > pi/2 and x <= pi :
return f*sin(pi-x)
elif x > pi and x <= 3*pi/2 :
return -f*sin(x-pi)
elif x > 3*pi/2 :
return -f*sin(2*pi-x)
else :
return f*sin(x)
def mytan(x) :
if x >= 0 and x <= pi/2 :
return tan(x)
else :
f = +1
if x < 0 :
x = -x
f = -1
while x >= 2*pi :
x = x - 2*pi
if x > pi/2 and x <= pi :
return -f*tan(pi-x)
elif x > pi and x <= 3*pi/2 :
return f*tan(x-pi)
elif x > 3*pi/2 :
return -f*tan(2*pi-x)
else :
return f*tan(x)
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