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Re: odd mathematica blindspot


Hi Ed,

By definition, 9999999999999/10000000000000 is an exact rational number, whereas 0.5 is an approximate real number:

In[2]:=
0.5===1/2

Out[2]=
False

In[9]:=
9999999999/10000000000===0.9999999999

Out[9]=
False

In[10]:=
9999999999./10000000000===0.9999999999

Out[10]=
True

So:

In[11]:=Solve[(9999999999999/10000000000000)^x == .5, x]
Out[11]={}

In[12]:=Solve[(9999999999999./10000000000000)^x == .5, x]
Out[12]={{x -> 6.937016409072274`*^12}}

Skirmantas


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