To be precise, I want to code in the function f(x,y) that gives 1/x if x = y + 1/2 and (-1/(1+x)) if x = y - 1/2 (no other pairs (x,y) satisfying neither will be considered). How?
This should do it?
f[x_, y_] := Which[x == y + 1/2, 1/x, x == y - 1/2, -1/(1 + x)(*,True,0*)] {f[1, 3/2], f[2, 3/2], f[6, 3/2]} {-1/2, 1/2, Null}
You can also define f separately for the two conditions by placing a constraint on the pattern matching. When neither constraint is met, f is undefined and so is returned unevaluated.
In[1]:= f[x_, y_] := 1/x /; x == y + 1/2 In[2]:= f[x_, y_] := -1/(1 + x) /; x == y - 1/2 In[4]:= f[1, 3/2] Out[4]= -(1/2) In[5]:= f[2, 3/2] Out[5]= 1/2 In[6]:= f[1, 1] Out[6]= f[1, 1]
Perfect, thanks a lot!
Thank you!
