fptan
Replace stack element 0 with its tangent and push a value of 1 onto the FPU stack.
fptan
fpatan
Divide stack element 1 by stack element 0, compute the arctangent and return the result in radians to stack element 1, then pop the stack.
fpatan
f2xm1
Replace the contents of stack element 0 (st) with the value of (2st-1).
f2xm1
fyl2x
Compute the logarithm (base-2) of stack element 0 and multiply the result by stack element 1 and return the result to stack element 1, then pop the stack.
fy12x
fyl2xp1
Compute the logarithm (base-2) of stack element 0 plus 1.0 and multiply the result by stack element 1 and return the result to stack element 1, then pop the stack.
fy12xpl