def setResultBox(self, textBox, value):
if value is not None:
self.valueFromTextBox[textBox] = value
textBox.setText(util.displayWithUnitsNumber(util.roundSigFig(value, 5), textBox.unit))
textBox.setCursorPosition(0)
else:
self.unsetValue(textBox)
def goalSeek(self):
# Newton's method
variableTextBox = self.textBox[self.ui.vary.currentText()]
resultTextBox = self.textBox[self.ui.target.currentText()]
self.ui.solverResult.setText('Searching...')
maximumIterations = 1000
success = False
dxFactor = 1e-9
try:
x0 = self.valueFromTextBox[variableTextBox]
except KeyError:
x0 = dxFactor
bestX = x0
try:
goal = util.convertUnitsStringToNumber(self.ui.lineEdit.text(), resultTextBox.unit)
y0 = self.calculateValue(variableTextBox, x0, resultTextBox)
bestError = abs((y0-goal)/goal)
for i in range(maximumIterations):
try:
y0 = self.calculateValue(variableTextBox, x0, resultTextBox)
error = abs((y0-goal)/goal)
if error < 1e-6:
success = True
break
else:
if error < bestError:
bestX = x0
bestError = error
dx = abs(dxFactor*x0)
slope = self.calculateSlope(variableTextBox, x0, dx, resultTextBox)
x0 = x0 - (y0-goal)/slope
if x0 < 0:
x0 = dx
except (ZeroDivisionError, KeyError, OverflowError):
dxFactor = 2*dxFactor
x0 = x0+dx
except ValueError: # "goal" is blank -> find extrema by Newton's method on slope
dx = abs(dxFactor*x0)
bestSlope = abs(self.calculateSlope(variableTextBox, x0, dx, resultTextBox))
for i in range(maximumIterations):
try:
dx = abs(dxFactor*x0)
slope = self.calculateSlope(variableTextBox, x0, dx, resultTextBox)
if abs(slope) < 1e-6:
success = True
break
else:
if slope < bestSlope:
bestX = x0
bestSlope = slope
secondDerivitive = self.calculateSecondDerivitive(variableTextBox, x0, dx, resultTextBox)
x0 = x0 - (slope)/secondDerivitive
if x0 < 0:
x0 = dx
except (ZeroDivisionError, KeyError, OverflowError):
dxFactor = 2*dxFactor
x0 = x0+dx
if success:
value = x0
self.ui.solverResult.setText('Success.')
else:
value = bestX
self.ui.solverResult.setText('Failed. Could not find a solution.')
variableTextBox.setText(util.displayWithUnitsNumber(util.roundSigFig(value, 5), variableTextBox.unit))
variableTextBox.setCursorPosition(0)
self.calculateAll()
