def find_idx_with_nonzero(self, coeficient_idx, start_idx=0):
"""Find the first equation index where coeficient "coeficient_idx" is not zero.
Args:
coeficient_idx(int): The index of the coefficient to check.
start_idx(int): Start the search in this row of the system.
Returns:
bool: Returns False if there is not an equation in this system
with coefficient "coeficient_idx" different than zero.
int: Returns the index of the equation with the first non-zero
coefficient in variable "coeficient_idx". Default value is
zero.
Raises:
IndexError: If start_idx is out of the bounds of self.planes array.
"""
for i in range(start_idx, len(self.planes)):
row_var_value = self.planes[i].normal_vector[coeficient_idx]
row_var_value = MyDecimal(row_var_value)
if(not row_var_value.is_near_zero()):
return i
return False
def compute_triangular_form(self):
"""This function will return a different copy of this system in triangular form.
Returns:
LinearSystem: A new system equals to this one in triangular form.
"""
system = deepcopy(self)
n = system.dimension
j= 0
for i,_ in enumerate(system.planes):
while j < n:
c = MyDecimal(system.planes[i].normal_vector[j])
if c.is_near_zero():
row_with_nonzero = system.find_idx_with_nonzero(j, i)
if row_with_nonzero:
system.swap_rows(i, row_with_nonzero)
else:
j += 1
continue;
system.clear_var(i,j)
j += 1
break;
return system
def get_first_col_where_one_coefficient_is_zero_and_other_no(self,row,row2):
for col in range(0,self.dimension):
coefficient_row = 0 if MyDecimal(self.planes[row].normal_vector[col]).is_near_zero() else self.planes[row].normal_vector[col]
coefficient_row2 = 0 if MyDecimal(self.planes[row].normal_vector[col]).is_near_zero() else self.planes[row2].normal_vector[col]
one_is_zero_but_not_both = coefficient_row * coefficient_row2 == 0 and (coefficient_row + coefficient_row2 != 0)
if(one_is_zero_but_not_both):
return col
return None
def var_count(self):
"""Returns a count of the number of variables present in the equation.
Returns:
int: Count of variables in this plane's equation.
"""
var_count = 0;
for _, coefficient in enumerate(self.normal_vector):
var_coefficient = MyDecimal(coefficient)
if(not var_coefficient.is_near_zero()):
var_count += 1
return var_count
def is_same_as(self, l2):
"""Check if self and l2 are the same.
Args:
l2(line.Line): We will check if self and this line are the same.
Returns:
bool: True if self and l2 are the same line. False otherwise.
Raises:
ValueError: If self and l2 normal vectors doesn't have the same dimensions.
"""
if (self.normal_vector.is_zero() and l2.normal_vector.is_zero()):
diff = self.constant_term - l2.constant_term
return MyDecimal(diff).is_near_zero()
atLeastOneZero = self.normal_vector.is_zero(
) or l2.normal_vector.is_zero()
if (atLeastOneZero):
return False
areParallel = self.is_parallel_to(l2)
if (not areParallel):
return False
vectorBetweenLines = self.basepoint - l2.basepoint
return vectorBetweenLines.is_orthogonal_to(
self.normal_vector) and vectorBetweenLines.is_orthogonal_to(
l2.normal_vector)
def is_same_as(self,p2):
"""Check if self and p2 are the same plane.
Args:
p2(plane.Plane): The plane to check against.
Returns:
bool: True if self and p2 are the same plane, false otherwise.
Raises:
ValueError: If self and p2 normal vectors doesn't have the same
dimensions.
"""
if(self.normal_vector.is_zero() and p2.normal_vector.is_zero()):
diff = self.constant_term - p2.constant_term
return MyDecimal(diff).is_near_zero()
atLeastOneZero = self.normal_vector.is_zero() or p2.normal_vector.is_zero()
if(atLeastOneZero):
return False
areParallel = self.is_parallel_to(p2)
if(not areParallel):
return False
vectorBetweenLines = self.basepoint - p2.basepoint
return vectorBetweenLines.is_orthogonal_to(self.normal_vector) and vectorBetweenLines.is_orthogonal_to(p2.normal_vector)
def solve(self):
"""Returns the solution of this system of equation.
Returns:
vector.Vector: If there is an unique solution, will return a vector
representing the x,y,z points of the solution.
bool: False if there is no solution and True if there are many
solutions.
"""
rref = self.compute_rref()
unique_solution = ['0','0','0']
first_nonzeros = rref.indices_of_first_nonzero_terms_in_each_row()
response = None
one_variable_alone = False
single_solution = True
for i,plane in enumerate(rref.planes):
pivot_var_idx = first_nonzeros[i]
constant_term = MyDecimal(plane.constant_term)
if(pivot_var_idx < 0 and not constant_term.is_near_zero() ):
return False
number_of_vars = rref[i].var_count()
if(number_of_vars == 1):
one_variable_alone = True
unique_solution[pivot_var_idx] = plane.constant_term/plane.normal_vector[pivot_var_idx]
elif(number_of_vars > 1):
single_solution = False
if(one_variable_alone and not single_solution):
response = False
elif(not one_variable_alone and not single_solution):
response = True
else:
response = unique_solution
return response
def first_nonzero_index(iterable):
"""Returns the index of the first non-zero value for the iterable.
Returns:
int: The index first nonzero value of the iterable.
Raises:
Exception: If all values in the iterable are zero.
"""
for k, item in enumerate(iterable):
if not MyDecimal(item).is_near_zero():
return k
raise Exception(Line.NO_NONZERO_ELTS_FOUND_MSG)
def first_nonzero_index(iterable):
"""Returns the index of the first non-zero value in iterable.
Args:
iterable(iterable): The iterable to search in.
Returns:
int: The index of the first non-zero value of iterable.
Raises:
Exception: If all items are zero.
"""
for k, item in enumerate(iterable):
if not MyDecimal(item).is_near_zero():
return k
raise Exception(Plane.NO_NONZERO_ELTS_FOUND_MSG)
