program main
implicit none
real a,b,h,x,y,s,p
integer i,n,sgn
a=0.1
b=1.
h=0.1
n=120
x=a
do while (x<b+h/2.)
s=0
p=1
sgn = 1
y=((1+x*x)/2)*atan(x)-x/2
do i=1, n
p=sgn * ((x**(2*i+1))/(4*(i**2)-1))
s=s+p
sgn = -sgn
end do
print *, 'x=', x, 'y=', y, ' s=', s
x=x+h
end do
end