如何在Semilogx图中绘制x = 0? [英] How to plot x=0 in semilogx plot?

问题描述

我需要使用semilogx(x,y)绘制图形.我有x=[0 1 2 ... 10 15 20 30 50 75 100].问题是MATLAB无法绘制x=0，我理解这是因为log(0)=undef.那么MATLAB中还有另一种传播观点的方法吗?因为使用线性比例会挤压图宽度的1/10的所有第一点！

I need to plot a graph using semilogx(x,y). I have x=[0 1 2 ... 10 15 20 30 50 75 100]. The problem is that MATLAB does not plot x=0, which I understand because log(0)=undef. So is there another method in MATLAB to spread my points? Because using linear scale squeezes all first points in 1/10th of the graph's width!

推荐答案

通常，在这种情况下要做的就是向所有x添加1，因此第一个值(最初为0)出现在所有值的反向转换都是相同的.您可以添加除1以外的任何其他小值，并获得类似的结果.但是，您不希望添加太小的 值(例如eps)，因为这样会使您与下一个值相距很远，这将导致所有其他值堆积在图的右侧.

Usually, what is done in cases like this is adding 1 to all x, so the first value (originally 0) appears at the origin, and also the back-transformation is the same for all values. You can add any other small values than 1, and get a similar result. However, you don't want to add a value that is too small (like eps) because then you get a huge distance from the next value, that will cause all other values to pack on the right side of the graph.

让我们看一个例子:

x = [0 logspace(0,2,5)];
% x =  0    1    3.1623    10    31.623    100
y = 2.*(x+1); % add 1 to all x
semilogx(x+1,y,'o','markerfacecolor','b') 

如果将0替换为eps，则会得到:

While if you replace 0 with eps you get:

x = [0 logspace(0,2,5)];
y = 2.*(x+eps); % add a tiny value too all x
semilogx(x+eps,y,'o','markerfacecolor','b')

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