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   sci.math.symbolic      Symbolic algebra discussion      10,432 messages   

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   Message 8,846 of 10,432   
   Axel Vogt to Richard Fateman   
   Re: on sin(very large number)   
   05 Aug 15 22:37:27   
   
   From: &noreply@axelvogt.de   
      
   On 05.08.2015 08:08, Richard Fateman wrote:   
   > On 8/4/2015 5:12 AM, Waldek Hebisch wrote:   
   >> Nasser M. Abbasi  wrote:   
   >>> I was answering someone question on Matlab forum, and noticed   
   >>> something interesting.   
   >>>   
   >>> Maple:   
   >>> ========   
   >>> Digits::60: sin(2*10^30): evalf(%);   
   >>> 0.17950046751493908795061771231643809505098047699633484280836744\   
   >>>    698514457349325219   
   >>>   
   >>> Matematica:   
   >>> ===========   
   >>> In[21]:= N[Sin[2*10^30], 60]   
   >>> Out[21]= 0.179500467514939087950617712316438095050980476996334842808367   
   >>>   
   >>> Mupad:   
   >>> ======   
   >>> Digits:=60:   
   >>> simplify(sin(2.0*10^30));   
   >>> -0.6054240282319655434839500429688996518962085247039794921875   
   >>>   
   >>> But when calling mupad from Matlab, now it gives different answer   
   >>> (same as Maple and Mathematica)   
   ...   
   Adding to the answers:   
      
   1. 30 + 15+3 Digits should do without tricks   
      
   2. Floats 2.0*10^30 equals 3552713678800501/4503599627370496*pow(2,101) in   
       IEEE double, 6617445/8388608*pow(2,101) in single, now try sinus in   
       various or above precision to judge results   
      
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