fitting module

lys.fitting.addFittingFunction(func, name)[source]

Add fitting function to the lys fitting module.

Use lys.functions.registerFittingFunction() instead of this function.

List of pre-defined fitting functions

lys.fitting.Functions.const(x, C)[source]

Function for fitting.

$y = C$

lys.fitting.Functions.cos(x, position, height, frequency, phase)[source]

Cosine function

$y = h \cos(f(x-x_0)+\phi)$

Parameters

position – $x_0$ .
height – $h$ .
frequency – $f$ .
phase – $\phi$ .

lys.fitting.Functions.doubleExp(x, position, height, a, b)[source]

Double exponential function with step.

$y = h\theta (x-x_0)(1-\exp[-(x-x_0)/a]^2)\exp[-(x-x_0)/b]$

Parameters

position – $x_0$ .
height – $h$ .
a – $a$ .
b – $b$ .

lys.fitting.Functions.error(x, position, height, fwhm)[source]

Error function for fitting.

For convenience, this function is defined as

$h(\mathrm{erf}[(x-x_0)/\tau] + 1)/2$

erf is error function (scipy.special.erf).

FWHM is of gaussian function integrated.

Parameters

position – $x_0$ .
height – $h$ .
fwhm – : $2\sqrt{\log 2}\tau$ .

lys.fitting.Functions.exp(x, position, height, a)[source]

Simple exponential function

$y=h\exp(a(x-x_0))$

Parameters

position – $x_0$ .
height – $h$ .
a – $a$ .

lys.fitting.Functions.gauss(x, position, height, sigma)[source]

Simple gaussian

$y=h\exp[-(x-x_0)^2/2\sigma^2]$

Parameters

position – $x_0$ .
height – $h$ .
sigma – $\sigma$ .

lys.fitting.Functions.linear(x, a=1, b=0)[source]

Function for fitting.

$y = ax + b$

lys.fitting.Functions.lorentz(x, position, height, fwhm)[source]

Lorentz function.

$y = hd^2/[(x-x_0)^2+d^2]$

Parameters

position – $x_0$ .
height – $h$ .
fwhm – $2d$ .

lys.fitting.Functions.quadratic(x, a, b, c)[source]

Function for fitting.

$y = ax^2 + bx + c$

lys.fitting.Functions.relaxOsci(x, position, height, frequency, phase, offset, tau)[source]

Relaxed ocillation.

$y=h(C + cos[f(x-x_0)+\phi])\exp[-(x-x_0)/\tau]\theta(x-x_0)$

Parameters

position – $x_0$ .
height – $h$ .
frequency – $f$ .
phase – $\phi$ .
offset – $C$ .
tau – $\tau$ .

lys.fitting.Functions.step(x, position, height)[source]

Heaviside step function for fitting.

$y = h \theta(x-x_0)$

Parameters

position – $x_0$ .
height – $h$ .

lys.fitting.Functions.stepExp(x, position, height, a)[source]

Exponential decay multiplied by step function.

$y = h\theta(x-x_0)\exp[-a(x-x_0)]$

Parameters

position – $x_0$ .
height – $h$ .
a – $a$ .