Olivier Ramare on Fri, 26 Feb 2010 11:11:44 +0100


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Strange behaviour of intnum


Hello,

 (1)----------------------------------------------------------------------

Can anyone tell me what wrong with

intnum(t = [0,0], [1], (sin(t)/t)^2)

Gp answers

? intnum(t = [0,0], [1], (sin(t)/t)^2)
 ***   at top-level: intnum(t=[0,0],[1],(sin(t)/t)^2)
 ***                                     ^------------
 *** sin: precision too low in mpsc1.

intnum(t = [0,0], 10000, (sin(t)/t)^2)
is ok, though the precision is of course fairly awful.

 (2) ----------------------------------------------------------------------

intnum(t = [0,0], 1000, 9*((sin(t)-t*cos(t))/t^3)^2)

is -- 0 !!!
-------------------------------------------------------------------------
? intnum(t = [0,0], 1000, 9*((sin(t)-t*cos(t))/t^3)^2)
%19 = 0.E94
? intnum(t = 0.00001, 1000, 9*((sin(t)-t*cos(t))/t^3)^2)
%20 = 1.884938921515439810798085699
---------------------------------------------------------------------------
intnum(t = 0.00001, [1], 9*((sin(t)-t*cos(t))/t^3)^2)
 ***   at top-level: intnum(t=0.00001,[1],9*((sin(t)-t*cos(t))/t^3
 ***                                          ^--------------------
 *** sin: precision too low in mpsc1.
---------------------------------------------------------------------------

Many thanks!
Amities,
             Olivier