(The third layer was created to present only 0 data.)
The range between the plus/minus minimum values around zero (in this sample, ☑0E-4) is actually an infinitely wide gap with no data like an “abyss”. Layer1 is used for positive region and layer2 is used for negative region. One method is to set up multiple layers for negative side and positive side separately. To realize this approach in Origin, there are two methods to implement. We can separately plot negative data as log(|x|) flipped in the third/forth quadrant. 5 Log(|x|) scale in separate positive/ negative layers To overcome the drawbacks of above three methods, Fig. Similar to 2), this method should be avoided unless the absolute value of the data never goes less than 1.Ĥ) y’ = log(|y|) in separate positive/negative regions: However, the biggest problem of this method is that the converted data cannot no longer depict the exponential trend as a straight line. This method actually resolves the above discontinuity problem in 2), and when uphill or downhill of the original data and the converted data change synchronically. We should avoid this method unless the absolute value of the data never enters less than 1.ģ) y’ = sign(y)*log(1 + |y| ): This formula is so-called Log-Modulus transformation. Of course, this approach is okay if data stays only within the positive region.Ģ) y’ = sign(y)*Log(|y|): You may first think that it’s a good idea, but when the original y value goes smaller that 1, a problem occurs – if the value is negative, the output of this function (y’) becomes positive, though when the value is positive, the output becomes negative! E.g. 2 Simple log scaleġ) y’=Log(y) : If you simply plot the data in log scale, you obviously cannot visualize the data in the negative range as in Fig. How can we present such data in a graph? For example in Fig.1, you see the sample curve in linear scale where the curve changes exponentially in both positive and negative directions separately. The logarithm of a negative value is not defined in the real space.īut in practical applications, we occasionally see that the magnitude of the data changes exponentially even in the negative area. Introduction: Fig.1 Sample in Linear Scale
0 kommentar(er)
