Class: OhmsLawCalculator

Inherits:
Object
  • Object
show all
Includes:
ActiveModel::Attributes, ActiveModel::Model
Defined in:
lib/ohms_law_calculator.rb

Class Method Summary collapse

Instance Method Summary collapse

Class Method Details

.calc(attributes) ⇒ Object

Voltage (V) = Current (I) * Resistance (R)
Power (P) = Voltage (V) * Current (I)



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# File 'lib/ohms_law_calculator.rb', line 13

def self.calc(attributes)
  new(attributes).calc
end

.difference_in_percent(number1, number2) ⇒ Object 



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# File 'lib/ohms_law_calculator.rb', line 46

def self.difference_in_percent(number1, number2)
  return 100.0 if number1.nil? || number2.nil?
  d = (BigDecimal((number1 - number2).abs) / number1) * 100
  d.round(1)
end

.validate(attributes, tolerance: 5.0) ⇒ Object 



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# File 'lib/ohms_law_calculator.rb', line 17

def self.validate(attributes, tolerance: 5.0)
  original_attributes = attributes.dup
  orig_resistance = attributes[:resistance]
  orig_voltage = attributes[:voltage]
  orig_current = attributes[:current]
  orig_power = attributes[:power]
  calc = new(attributes).calc
  resistance_diff = difference_in_percent(calc.resistance, orig_resistance)
  voltage_diff = difference_in_percent(calc.voltage, orig_voltage)
  current_diff = difference_in_percent(calc.current, orig_current)
  power_diff = difference_in_percent(calc.power, orig_power)

  # compare
  errors = []
  if resistance_diff > tolerance
    errors << "Resistance (Ohm) invalid. #{orig_resistance || 'nil'} different than calculated  #{calc.resistance} by #{resistance_diff} %"
  end
  if voltage_diff > tolerance
    errors << "Voltage invalid. #{orig_voltage || 'nil'} different than calculated #{calc.voltage} by #{voltage_diff} %"
  end
  if current_diff > tolerance
    errors << "Current (Amps) invalid. #{orig_current || 'nil'} different than calculated #{calc.current} by #{current_diff} %"
  end
  if power_diff > tolerance
    errors << "Power (Watts) invalid. #{orig_power || 'nil'} different than calculated #{calc.power} by #{power_diff}"
  end
  errors
end

Instance Method Details

#calc ⇒ Object 



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# File 'lib/ohms_law_calculator.rb', line 52

def calc
  Rails.logger.debug "Ohms Law Calculator Inputs: #{attributes.inspect}"
  if self.voltage && self.current
    self.resistance = BigDecimal(self.voltage) / self.current
    self.power = (self.voltage * self.current).round
  elsif self.voltage && self.resistance
    self.current = BigDecimal(self.voltage) / self.resistance
    self.power = (BigDecimal(self.voltage**2) / self.resistance).round
  elsif self.voltage && self.power
    self.current = BigDecimal(self.power) / self.voltage
    self.resistance = BigDecimal(self.voltage**2) / self.power
  elsif self.current && self.resistance
    self.voltage = self.current * self.resistance
    self.power = (self.current**2 * self.resistance).round
  elsif self.current && self.power
    self.voltage = BigDecimal(self.power) / self.current
    self.resistance = BigDecimal(self.power) / self.current**2
  elsif self.resistance && self.power
    self.voltage = Math.sqrt(power * self.resistance)
    self.current = Math.sqrt(BigDecimal(watts) / ohms)
  elsif self.voltage
    self.current = nil
    self.power = nil
    self.resistance = nil
  elsif self.current
    self.voltage = nil
    self.power = nil
    self.resistance = nil
  elsif self.resistance
    self.voltage = nil
    self.current = nil
    self.power = nil
  elsif self.power
    self.voltage = nil
    self.current = nil
    self.resistance = nil
  end
  self.power = self.power&.round
  self.voltage = self.voltage&.round
  self.current = self.current&.round(4)
  self.resistance = self.resistance&.round(5)
  OpenStruct.new(attributes.symbolize_keys).freeze
end