integrate of bessel_i sign error?

integrate doesn't seem to give a correct value
for the integral of bessel_i, based on numerical
 values Maxima uses.

For a small integration range and a smooth
function, a rough value of the integral
is base*height. Here we use a base = 1
integrating from y = 1 to y = 2,
and use a height the  value 
half way across the range:

(%i1) load(nint);
(%o1) "c:/work2/nint.mac"
(%i2) ratprint:false$
(%i3) f(a):= fchop(expand(float(a)))$

here is the height:

(%i4) f(bessel_i(1,%i*1.5));
(%o4) 0.5579365079101*%i

here is the integral over a range = 1:

(%i5) f(integrate(bessel_i(1,%i*y),y,1,2));
(%o5) -0.54130690741673*%i

integrate appears to produce the wrong sign
for this integral??


Ted Woollett