目录

一.语法

二.说明

三.示例

1.复数的幅值和相位

2.FFT 相位

angle函数是求解相位角。

一.语法

theta = angle(z)


z - 输入数组


输入数组，指定为标量、向量、矩阵或多维数组。如果 z 的元素是非负实数，则 angle 返回 0。如果z的元素是负实数，则 angle返回 π。

数据类型： double | single
复数支持： 是

二.说明


theta = angle(z) 为复数数组 z 的每个元素返回区间 [-π,π] 中的相位角。theta 中的角度表示为 z = abs(z).*exp(i*theta)。


三.示例

1.复数的幅值和相位

创建一个复数，并计算其幅值和相位。如下所示：

z = 2*exp(i*0.5)
z = 1.7552 + 0.9589i

r = abs(z)
r = 2

theta = angle(z)
theta = 0.5000

2.FFT 相位

创建一个由频率为 15 Hz 和 40 Hz 的两个正弦波组成的信号。第一个正弦波的相位为 −π/4，第二个正弦波的相位为π/2。以 100Hz的频率对信号进行一秒钟的采样。

fs = 100;
t = 0:1/fs:1-1/fs;
x = cos(2*pi*15*t - pi/4) - sin(2*pi*40*t);

计算信号的傅里叶变换。将变换幅值绘制为频率函数。

y = fft(x);
z = fftshift(y);

ly = length(y);
f = (-ly/2:ly/2-1)/ly*fs;

stem(f,abs(z))
xlabel 'Frequency (Hz)'
ylabel '|y|'
grid

如图所示：



计算变换的相位，删除小幅值变换值。将相位绘制为频率函数。

tol = 1e-6;
z(abs(z) < tol) = 0;

theta = angle(z);

stem(f,theta/pi)
xlabel 'Frequency (Hz)'
ylabel 'Phase / \pi'
grid

如图所示：



 

Starting with R2009b, the sim command was enhanced to provide greater compatibility with parallel computing. The improved single-output format saves all simulation results to a single object, simplifying the management of output variables.

For backward compatibility with R2009a or earlier releases, use the backward-compatible syntax:

[T,X,Y] = sim('model',Timespan, Options, UT)

[T,X,Y1,...,Yn] = sim('model',Timespan, Options, UT)

If you specify only the model argument, Simulink automatically saves the time, state, and output to the specified output arguments.

If you do not specify any output arguments, Simulink determines what data to log based on the settings for the Configuration Parameters > Data Import/Export pane. Simulink stores the simulation output either in the current workspace or in the variable ans, based on the setting for Save simulation output as a single object parameter.

Backward-Compatible Syntax Input and Output Arguments

Argument    Description

T
			

			
The time vector returned.
			
		
X
			

			
The state returned in matrix or structure format. The state matrix contains continuous states followed by discrete states.
			
		
Y
			

			
The output returned in matrix or structure format. For block diagram models, this variable contains all root-level blocks.
			
		
Y1,...,Yn
			

			
The outports, which can only be specified for diagram models. Here, n must be the number of root-level blocks. Each outport will be returned in the Y1,...,Yn variables.
			
		
'model'
			

			
The name of the model to simulate.
			
		
Timespan
			

			
The timespan can be TFinal, [TStart TFinal], or [TStart OutputTimes TFinal]. Output times are time points returned in T, but in general, T includes additional time points.
			
		
Options
			

			
Optional simulation parameters created in a structure by the simset command using name-value pairs.
			
		
UT
			

			
Optional external inputs. For supported expressions, see Load Data to Root-Level Input Ports.
			
		

1，rand 生成均匀分布的伪随机数。分布在（0~1）之间

   主要语法：rand(m,n)生成m行n列的均匀分布的伪随机数

                      rand(m,n,'double')生成指定精度的均匀分布的伪随机数，参数还可以

                     是'single'

                     rand(RandStream,m,n)利用指定的RandStream(我理解为随机种子)生成伪

                     随机数


2，randn 生成标准正态分布的伪随机数（均值为0，方差为1）

     主要语法：和上面一样


3, randi 生成均匀分布的伪随机整数

     主要语法：randi（iMax）在开区间（0，iMax）生成均匀分布的伪随机整数

                       randi（iMax，m，n）在开区间（0，iMax）生成mXn型随机矩阵
                       r = randi([iMin,iMax],m,n)在开区间（iMin，iMax）生成mXn型随机矩阵

I find it impossible to write MATLAB code without creating a huge number of superfluous, single-use variables.
For example, suppose function foo returns three column vectors of exactly the same size.  Say:
function [a, b, c] = foo(n)
a = rand(n, 1);
b = rand(n, 1);
c = rand(n, 1);
end
Now, suppose that bar is a function that expect as imput a cell array of size (1, 3).
function result = bar(triplet)
[x, y, z] = triplet{:};
result = x + y + z;
end
If I want to pass the results of foo(5), I can do it by creating three otherwise-useless variables:
[x, y, z] = foo(5);
result = bar({x, y, z});
Is there some function baz that would allow me to replace the two lines above with
result = bar(baz(foo(5)));
?
NB: the functions foo and bar above are meant only as examples.  They're supposed to represent functions over which I have no control.  IOW, modifying them is not an option.
解决方案
Not possible. baz in baz(foo(5)) will only take the first output of foo, the other two would be ignored. The plain two-line variant is not that awkward. And this is not a common situation. You don't generally work with cell arrays where normal numerical arrays would do.
You could of course just write your own wrapper for foo that returns whatever you need (i.e. containing similar two lines), in case you need to use it frequently.