/ ___ ___\ / ___ ___\ / ___ ___\ / ___ ___\ | \/ 2 I*\/ 2 | | \/ 2 I*\/ 2 | | \/ 2 I*\/ 2 | | \/ 2 I*\/ 2 | (a + 1)*(a - 1)*(a + I)*(a - I)*|a + ----- + -------|*|a + ----- - -------|*|a + - ----- + -------|*|a + - ----- - -------| \ 2 2 / \ 2 2 / \ 2 2 / \ 2 2 /