1516
1516
sample range or to produce an evenly spaced set from an irregular
1519
<P>Under the "Library" menu, several functions are available under the
1520
categories: "Gaussian Functions", "Lorentzian Functions", "Peak Functions",
1521
"Periodic Peak Functions" and "Baseline Functions".</P>
1523
<P><i>Gaussian</i><br>  y = A0 + (A3*2*sqrt(ln(2)/pi)/A2)*exp(-4*ln(2)*((x-A1)/A2)^2)<br>
1524
  where: A0: Baseline offset; A1: Center of the peak; A2: Full width at half
1525
maximum; A3: Peak area.<br> The center and initial amplitude of the peak can be set from
1526
user input (via mouse coordinates). </P>
1529
<P><i>Gaussian (Chromatography):</i><br>
1530
  y = A0 + (1/sqrt(2*pi))*(A3/A2)*exp(-(x-A1)^2/2*A2^2)
1531
A0: Baseline offset; A1: Center of the peak (retention time); A2:
1532
Standard deviation of the peak; A3: Peak area. <br> The center and initial amplitude of the peak can be set from
1533
user input (via mouse coordinates). </P>
1536
<P><i>Lorentzian</i><br>  y = A0 + (2*A2*A3/pi)/(4*(x-A1)^2 + A2^2)<br>
1537
  where: A0: Baseline offset; A1: Center of the peak; A2: Full width at half
1538
maximum; A3: Peak area. <br> The center and initial amplitude of the peak can be set from
1539
user input (via mouse coordinates).</P>
1542
<P><i>Peak Functions</i><br>
1543
<i>Pseudo Voigt 1</i><br>
1544
  y = A0 + A3 * (A4*(2/pi)*A2/(4*(x-A1)^2+A2^2) + <br>(1-A4)*exp(-4*ln(2)*(x-A1)^2/A2^2)*(sqrt(4*ln(2))/(A2*sqrt(pi))))<br>
1545
  where: Gaussian and Lorentzian have the same width; A0: Baseline offset;
1546
A1: Center of the peak; A2: Full width at half maximum; A3: Amplitude;
1547
A4: Profile shape factor.<br>
1548
<i>Pseudo Voigt 2</i><br>
1549
  y = A0 + A3 * (A5*(2/pi)*A2/(4*(x-A1)^2+A2^2) + (1-A5)*exp(-4*ln(2)*(x-A1)^2/A4^2)*(sqrt(4*ln(2))/(A2*sqrt(pi))))<br>
1550
  where: Gaussian and Lorentzian have different width; A0: Baseline offset;
1551
A1: Center of the peak; A2: Full width at half maximum; A3: Amplitude;
1552
A4: Profile shape factor.<br>
1553
<i>Doniach-Sunjic</i><br>
1554
  y = A0 + A3*cos((pi*A4/2)+(1-A4)*atan((x-A1)/A2))/(A2^2+(x-A1)^2)^((1-A4)/2)<br>
1555
  where:A0: Baseline offset; A1: Center of the peak; A2: Full width at half maximum;<br>
1556
 A3: Peak area; A4: Asymmetry parameter.<br>
1557
<i>Asymmetric double Sigmoidal</i><br>
1558
  y = A0 + A3*(1/(1+exp(-(x-A1+A2/2)/A4)))*(1-(1/(1+exp(-(x-A1-A2/2)/A5))))<br>
1559
  where: A0: Baseline offset; A1: Center of the peak; A2: Width 1;
1560
A3: Amplitude; A4: Width 2; A5: Width 5.<br>
1561
<i>Logarithm Normal:</i> <br>
1562
  y = A0 + A3*exp(-((ln(x)-ln(A1))^2)/(2*A2))<br>
1563
  where: A0: Baseline offset; A1: Center of the peak; A2: Width <br>
1564
<i>Gram-Charlier A-Series (GCAS)</i><br>
1565
  y = A0 + A3/(A2*sqrt(2*pi))*exp(-0.5*((x-A1)/A2)^2)*(1+(A4/6)*
1566
(((x-A1)/A2)^3-3*(x-A1)/A2)+(A5/24)*(((x-A1)/A2)^4-6*((x-A1)/A2)^3+3))<br>
1567
  where: A0: Baseline offset; A1: Center of the peak; A2: Standard deviation;
1568
A3: Peak Area; A4: Skew; A5: Excess. <br>
1569
<i>Edgeworth-Cramer Series</i><br>
1570
  y = A0 + A3/(A2*sqrt(2*pi))*exp(-0.5*((x-A1)/A2)^2)*(1+(A4/6)*
1571
(((x-A1)/A2)^3-3*(x-A1)/A2)+(A5/24)*(((x-A1)/A2)^4-6 *((x-A1)/A2)^3+3)
1572
+(A5^2/720)*(((x-A1)/A2)^6-15*((x-A1)/A2)^4+45*((x-A1)/A2)^2-15))<br>
1573
  where: A0: Baseline offset; A1: Center of the peak; A2: Standard deviation;
1574
A3: Peak Area; A4: Skew; A5: Excess. <br>
1575
<i>Inverse Polynomial</i><br>
1576
  y=A0+A3/(1+ A4*(2*(x-A1)/A2)^2 + A5*(2*(x-A1)/A2)^4 + A6*(2*(x-A1)/A2)^6) <br>
1577
  where: A0: Baseline offset; A1: Center of the peak; A2: Standard deviation;
1578
A3: Peak Area; A4, A5, A6: Parameters. <br>
1582
<P><i>Periodic Peak Functions</i><br>
1584
 y=A0+A3*sin(pi*(x-A1)/A2)<br>
1585
 where: A0: Baseline offset; A1: Center; A2: Width; A3: Amplitude.<br>
1586
<i>Sine Square: </i><br>
1587
 y=A0+A3*sin(pi*(x-A1)/A2)^2<br>
1588
 where: A0: Baseline offset; A1: Center; A2: Width; A3: Amplitude.<br>
1589
<i>Sine damp: </i><br>
1590
 y=A0+A3*exp(-x/A4)*sin(pi*(x-A1)/A2)<br>
1591
 where: A0: Baseline offset; A1: Center; A2: Width; A3: Amplitude; A4: Decay time. <br>
1595
<P><i>Baseline Functions</i><br>
1596
<i>Exponential Decay 1:</i><br>
1597
y=A0+A3*exp(-(x-A1)/A2)<br>
1598
<b>Exponential Decay 2:</b> <br>
1599
y=A0+A3*exp(-(x-A1)/A2)+A6*exp(-(x-A4)/A5);<br>
1600
<i>Exponential Growth 1:</i> <br>
1601
y=A0+A3*exp((x-A1)/A2)<br>
1602
<i>Exponential Growth 2: </i><br>
1603
y=A0+A3*exp(-(x-A1)/A2)+A6*exp((x-A4)/A5);<br>
1604
<i>Hyperbolic:</i><br>
1605
y=A0+(A1*x)/(A2+x)<br>
1606
<i>Bradley:</i> <br>
1607
y=A0*ln(-A1*ln(x))<br>
1608
<i>Logarithm 3 Parameters: </i><br>
1609
y=A0-A1*ln(x+A2)<br>
1519
1612
<H3><A NAME="correlation/covariance"></A> Correlation/covariance </H3>
1521
1614
<P>This popup can be used to compute autocorrelation