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# semilogy

Semilogarithmic plot

## Syntax

semilogy(Y)
semilogy(X1,Y1,...)
semilogy(X1,Y1,LineSpec,...)
semilogy(...,'PropertyName',PropertyValue,...)
h = semilogy(...)

## Description

semilogy plots data with logarithmic scale for the y-axis.

semilogy(Y) creates a plot using a base 10 logarithmic scale for the y-axis and a linear scale for the x-axis. It plots the columns of Y versus their index if Y contains real numbers. semilogy(Y) is equivalent to semilogy(real(Y), imag(Y)) if Y contains complex numbers. semilogy ignores the imaginary component in all other uses of this function.

semilogy(X1,Y1,...) plots all Yn versus Xn pairs. If only one of Xn or Yn is a matrix, semilogy plots the vector argument versus the rows or columns of the matrix, along the dimension of the matrix whose length matches the length of the vector. If the matrix is square, its columns plot against the vector if their lengths match.

semilogy(X1,Y1,LineSpec,...) plots all lines defined by the Xn,Yn,LineSpec triples. LineSpec determines line style, marker symbol, and color of the plotted lines.

semilogy(...,'PropertyName',PropertyValue,...) sets property values for all the charting lines created by semilogy. For a list of properties, see Chart Line Properties.

h = semilogy(...) returns a vector of chart line handles, one handle per line.

## Examples

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### Logarithmic Scale for y-Axis

Create a plot with a logarithmic scale for the y-axis and a linear scale for the x-axis.

```x = 0:0.1:10;
y = exp(x);

figure
semilogy(x,y)
```

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### Tips

If you do not specify a color when plotting more than one line, semilogy automatically cycle through the colors and line styles in the order specified by the current axes ColorOrder and LineStyleOrder properties.

You can mix Xn,Yn pairs with Xn,Yn,LineSpec triples; for example,

```semilogy(X1,Y1,X2,Y2,LineSpec,X3,Y3)
```

If you attempt to add a loglog, semilogx, or semilogy plot to a linear axis mode graph with hold on, the axis mode remains as it is and the new data plots as linear.