Question

I have a long expression that I would like to split into a collection of terms. For example say I have:

a + b - c + d + 4*e - 3*f

I want to split the expression by addition/subtraction into:

{a, b, -c, d, 4*e, -3*f}

My motivation for this is that I want to deal with the original expression term by term. Is this possible?

Edit: The examples given are VERY simplistic compared to what I’m actually dealing with in Mathematica, it’s just that I’m not sure how to write Math around here.

Answer 1

To split the expression, you need to use Level. Level gives you a list of subexpressions and you can specify the level at which you want the subexpressions returned. In this case, you need levelspec 1.

In[1]:= expr = a + b - c + d + 4 e - 3 f;
In[2]:= Level[expr, 1]

Out[2]= {a, b, -c, d, 4 e, -3 f}

An example with a slightly more complicated expression:

In[3]:= expr2 = a^2 + 5 bc/ef - Sqrt[g - h] - Cos[i]/Sin[j + k];
In[4]:= Level[expr2, 1]

Out[4]= {a^2, (5 bc)/ef, -Sqrt[g - h], -Cos[i] Csc[j + k]}