Add option to ignore data points which guarantee failure of Fit

[Roman Tolchenov]

Add a bool property to Fit to ignore NaNs, infinities and points with 0 error.

[Gesner Passos]

(In #6981) It was found that some requirements from Linear were different from Fit. After some discussion, it was agreed that implementing #7182 allows us to use Fit algorithm.

But, the error from the Linear and Fit using function LinearBackground are different, the reason is that Linear, calculates the errors as:

err = sqrt(s0² + x²s1² + 2s01²)

while fit calculates the erros as:

err = sqrt(s0² + x²s1²)

Where s0² is the covariance of the first parameter(c0), s1² is the covariance of the second parameter(c1), and s01² is the covariance between these two parameters. For the liner equation:

y = c0 + c1 x

The fit does the simplification of considering the parameters independent, which is acceptable for the generic approach that fit offers. So, changing from Linear to Fit will cause us to update the systemtests that used to use Linear mainly because the errors are different right now.

[Roman Tolchenov]

Added option to ignore invalid data in Fit. Re #7182.

Changeset: 0cca0b95f97b4f6abbd7d54f3765c4d67f0ce557

[Roman Tolchenov]

Merge branch 'feature/7182_fit_ignore_option' into develop

[Roman Tolchenov]

Disable windows warning. Re #7182.

Changeset: fe567e46eed87f9b69ea81905d1766bf5df6cc5f

[Roman Tolchenov]

Merge branch 'feature/7182_fit_ignore_option' into develop

[Gesner Passos]

Run this code and you will see that for error = nan the fit fail to give the desired result.

import numpy
import math
import sys

x = numpy.arange(5.0)
y = numpy.arange(5.0)
e = numpy.ones(5.0)

y[3] = 30
e[3] = numpy.inf

data = CreateWorkspace(x,y,e)
lin = Linear(data)

#data = Load('/home/gesner/fit_linear/linear_executed_over_this_input_workspace.nxs')
lin = Linear(data)
fit = Fit("name=LinearBackground",data,CreateOutput=True,IgnoreInvalidData=True)
print fit

Besides, Add the option IgnoreInvalidData to the FitDialog and to FitFunction dockwidget.

[Roman Tolchenov]

Added checks for error being nan or inf. Re #7182.

Changeset: 3a18cc7dc850cfb94516dbd1b21bcd8ed27e25b2

[Alex Buts]

no option to remove NaNs availible on interface and script:

from mantid.simpleapi import *
import numpy as np

Load(Filename=r'd:\Data\Mantid_GIT\Test\AutoTestData\MAR11001.raw',OutputWorkspace='MAR11001',LoadMonitors='Separate')

ws = mtd['MAR11001_Monitors']

xx = ws.dataX(1);
yy = ws.dataY(1);
ee = ws.dataE(1);

for i in xrange(0, len(xx)) :
    if xx[i]>6346 and xx[i]<6685:
        yy[i] = np.nan

does not work when trying to fit data around the pick from GUI

[Roman Tolchenov]

Added the option to ignore invalid data to fit browser. Re #7182.

Changeset: ac202b62a4d7737521548954a2bd1133b8b0bfd8

[Anders Markvardsen]

When fitting a spectrum with NaN get error message when NOT ignore invalid...:

Error in execution of algorithm Fit: Infinte number or NaN found in input data.

When ignore invalid... does correctly ignore NaN

[Stuart Campbell]

This ticket has been transferred to github issue ​8028