Tier 1 · precalculus

Complex Mult

Multiply two complex numbers (a+bi)(c+di).

Files (1)

COMPLEX.py317 bytes

def p(s):print(s)
def o1():
 p("=COMP MULT=")
 a=float(input("a:"))
 b=float(input("b:"))
 c=float(input("c:"))
 d=float(input("d:"))
 r=a*c-b*d
 i=a*d+b*c
 p("r="+str(r))
 p("i="+str(i))
def menu():
 while True:
  p("=COMPLEX=")
  p("1:MULT")
  p("0:EXIT")
  c=input("?>")
  if c=="1":o1()
  elif c=="0":break
menu()

How to use it

Launch COMPLEX from prgm. From the main menu pick 1:MULT to multiply two complex numbers.

For (a+bi)(c+di) the program asks for four numbers in order:

a: real part of the first number.
b: imaginary part of the first number.
c: real part of the second number.
d: imaginary part of the second number.

Output is the real part (r=) and imaginary part (i=) of the product. Press 0 from the menu to exit.

Example problem

Compute (1 + i)(2 − i).

Here a=1, b=1, c=2, d=−1.

Run COMPLEX, choose 1:MULT.
a: → 1, b: → 1, c: → 2, d: → -1.
Output: r=3.0, i=1.0.

Result: 3 + i. Verify by FOIL: 1·2 + 1·(−i) + i·2 + i·(−i) = 2 − i + 2i − i² = 2 + i + 1 = 3 + i. ✓

TI-84 Plus CE — try before committingoff

TI-84 Plus CE




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Test cases (2)

ID	Inputs	Expected contains
one-plus-i-times-two-minus-i	1, 1, 1, 2, -1, 0	r=3.0, i=1.0
i-times-i	1, 0, 1, 0, 1, 0	r=-1.0, i=0.0