def op_permutations(n, r):
"""Return the number of ways there are to arrange r things in n places, counting all orders"""
# invalid cases
if n % 1 != 0 or r % 1 != 0 or n < 0 or r < 0:
raise CalcOperationError(
"Both must be whole numbers and cannot be negative", "P", [n, r])
if r > n:
raise CalcOperationError(
"r ({}) cannot be greater than n ({})".format(r, n), "P", [n, r])
# use the factorial operation already defined
return op_factorial(n) / op_factorial(n - r)
def prime_factors(x):
"""Return a list of all of x's prime factors"""
# invalid cases
if x % 1 != 0 or x < 1:
raise CalcOperationError("Must be a positive whole number",
"LCM or HCF", [x])
# typical cases
factors = []
i = 2
# for each possible factor
while i**2 <= x:
# if it is a factor, add it and adjust x to prevent repeats
# don't increment i as more than 1 of the same factor is possible
if x % i == 0:
x //= i
factors.append(i)
# if it's not a factor, increment it to find the next
else:
i += 1
# add the last factor if x isn't 1
if x > 1:
factors.append(x)
return factors
def op_mod(x, y):
"""Return x mod y - the remainder when x is divided by y"""
# invalid case
if y == 0:
raise CalcOperationError("Cannot divide by 0", "%", [x, y])
# typical cases
return x % y
def op_floor_div(x, y):
"""Return x divided by y, rounded down"""
# invalid case
if y == 0:
raise CalcOperationError("Cannot divide by 0", "\\", [x, y])
# typical cases
return x // y
def op_true_div(x, y):
"""Return x divided by y"""
# invalid case
if y == 0:
raise CalcOperationError("Cannot divide by 0", "/", [x, y])
# typical cases
return x / y
def op_root(root, x):
"""Return the root th root of x"""
# invalid cases
if root <= 0 or root % 1 != 0:
raise CalcOperationError("The root must be a positive whole number",
"¬", [root, x])
# specific case of power
return x**(1 / root)
def op_exp(x, y):
"""Return x to the power of y"""
# invalid case
if x == 0 and y == 0:
raise CalcOperationError("0 to the power of 0 is undefined", "^",
[x, y])
# typical cases
return x**y
def func_ln(x):
"""Return ln(x)"""
# invalid cases
if x <= 0:
raise CalcOperationError(
"Can only find the natural log of positive numbers", "ln", [x])
# use the function from the 'math' library
return log(x)
def func_artanh(x):
"""Return artanh(x) where the answer is in radian"""
# invalid cases
if x <= -1 or x >= 1:
raise CalcOperationError(
"Inverse hyperbolic tangent is only defined for values between -1 and 1 exclusive",
"artanh", [x])
# use the function from the 'math' library
return atanh(x)
def func_arcosh(x):
"""Return arcosh(x) where the answer is in radians"""
# invalid cases
if x < 1:
raise CalcOperationError(
"Inverse hyperbolic cosine is undefined for values less than 1",
"arcosh", [x])
# use the function from the 'math' library
return acosh(x)
def func_arcos(x):
"""Return arcos(x) where the answer is in radians"""
# invalid cases
if x < -1 or x > 1:
raise CalcOperationError(
"Inverse cosine is only defined for values between -1 and 1 inclusive",
"arcos", [x])
# use the function from the 'math' library
return acos(x)
def func_log(x, base):
"""Return log of x to the base 'base'"""
# invalid cases
if x <= 0 or base <= 0:
raise CalcOperationError(
"Can only find the log of a positive number with a positive base",
"log", [base, x])
# use the function from the 'math' library
return log(x, base)
def func_tan(x):
"""Return tan(x) where x is in radians"""
from Datatypes import valid_tokens, Num
# invalid cases
if x % valid_tokens["pi"] == Num("0.5") * valid_tokens["pi"]:
raise CalcOperationError(
"Tangent is undefined for values half way between multiples of pi",
"tan", [x])
# use the function from the 'math' library
return tan(x)
def func_rand(low, high):
"""Return a random integer between 'low' and 'high'"""
# invalid cases
if low % 1 != 0 or high % 1 != 0:
raise CalcOperationError("Must be whole numbers", "rand", [low, high])
# if the wrong way around, swap them
if low > high:
low, high = high, low
# use the function from the 'random' library
return randint(low, high)
def func_quadn(a, b, c):
"""Return the positive square root answer of the quadratic equation ax^2 + bx + c = 0"""
from Datatypes import Num
discriminant = b**2 - 4 * a * c
# invalid cases
if discriminant < 0:
raise CalcOperationError("No real solutions", "quadn", [a, b, c])
# quadratic formula with negative square root
return (-b - discriminant**Num("0.5")) / (2 * a)
def op_factorial(x):
"""Return x factorial"""
# invalid cases
if x < 0 or x % 1 != 0:
raise CalcOperationError("Must be whole number and cannot be negative",
"!", [x])
# multiply all numbers between 1 and x together
product = 1
while x > 1:
product *= x
x -= 1
return product
