semilogx 2D semilogarithmic plot

## Syntax

                semilogx     // demo
                semilogx(y)
                semilogx(x, y)
                semilogx(x, fun)
                semilogx(x, list(fun, param))
                semilogx(.., LineSpec)
                semilogx(.., LineSpec, GlobalProperty)
                semilogx(x1, y1, LineSpec1, x2,y2,LineSpec2,...xN, yN, LineSpecN, GlobalProperty1,.. GlobalPropertyM)
                semilogx(x1,fun1,LineSpec1, x2,y2,LineSpec2,...xN,funN,LineSpecN, GlobalProperty1, ..GlobalPropertyM)
                semilogx(axes_handle,...)

## Arguments

x

  vector or matrix of strictly positive real numbers or integers. If omitted, it is assumed to be the vector `1:n` where `n` is the number of curve points given by the `y` parameter.

y

  vector or matrix of real numbers or of integers.

fun, fun1, ..

  handle of a function, as in `semilogx(x, sin)`.

  If the function to plot needs some parameters as input arguments, the function and its parameters can be specified through a list, as in `semilogx(x, list(delip, -0.4))`

LineSpec

  This optional argument must be a string that will be used as a shortcut to specify a way of drawing a line. We can have one `LineSpec` per `y` or `{x,y}` previously entered. `LineSpec` options deals with LineStyle, Marker and Color specifiers (see LineSpec). Those specifiers determine the line style, mark style and color of the plotted lines.

GlobalProperty

  This optional argument represents a sequence of couple statements `{PropertyName,PropertyValue}` that defines global objects' properties applied to all the curves created by this plot. For a complete view of the available properties (see GlobalProperty).

axes_handle

  This optional argument forces the plot to appear inside the selected axes given by `axes_handle` rather than the current axes (see gca).

## Description

`semilogx` plots data using a base 10 logarithmic scale for the x-axis and a normal (linear) scale for the y-axis. The possible syntaxes and arguments are the same as the plot function besides the condition that the abscisae values in

x
argument be strictly positive.

If the current axes is not empty and the the x-axis has a negative lower bound then its scale will remain linear after the plot.

Enter the command `semilogx` to see a demo.

## Examples

                w=logspace(-2,2,1000);
                s=%i*w;
                g=1../(s.^2+s+1);
                clf("reset")

                semilogx(w,abs(g));

                title("$\LARGE \left|1/(s^2+s+1)\right|\mbox{ for }s=i\omega$")
                xlabel("$\LARGE \omega$")

w=logspace(-2,2,1000); s=%i*w; g=1../(s.^2+s+1); clf("reset") semilogx(w,abs(g)); title("$\LARGE \left|1/(s^2+s+1)\right|\mbox{ for }s=i\omega$") xlabel("$\LARGE \omega$")

## See also

- plot
- semilogy
- loglog
- LineSpec
- GlobalProperty

## History

6.1.1 Function semilogx added.