索引超出数组元素的数目(0)。 tic_x=rect(1)+rect(3)/2;怎么改错

这个错误通常是因为你使用了空数组或者索引超出了当前数组的范围。在这种情况下，错误发生在 tic_x=rect(1)+rect(3)/2; 这一行，很可能是因为 rect 数组为空或者长度为 0。

要解决这个问题，你可以先检查一下 rect 数组是否为空或者长度为 0，如果是，那么请检查一下代码逻辑是否正确。另外，你也可以添加一些条件判断来确保你的代码不会访问不存在的数组元素，例如：

if ~isempty(rect) && length(rect) >= 3
    tic_x = rect(1) + rect(3)/2;
else
    % 处理 rect 为空或长度小于 3 的情况
    ...
end

上面的代码中，`~isempty(rect)` 表示当 rect 不为空时才会执行后面的代码。`length(rect) >= 3` 表示当 rect 的长度大于等于 3 时才会执行后面的代码。这样就可以避免访问不存在的数组元素，从而避免出现 "索引超出数组元素的数目" 的错误。

相关问题

clear all; close all; clc; tic bits_options = [0,1,2]; noise_option = 1; b = 4; NT = 2; SNRdBs =[0:2:20]; sq05=sqrt(0.5); nobe_target = 500; BER_target = 1e-3; raw_bit_len = 2592-6; interleaving_num = 72; deinterleaving_num = 72; N_frame = 1e8; for i_bits=1:length(bits_options) bits_option=bits_options(i_bits); BER=zeros(size(SNRdBs)); for i_SNR=1:length(SNRdBs) sig_power=NT; SNRdB=SNRdBs(i_SNR); sigma2=sig_power10^(-SNRdB/10)noise_option; sigma1=sqrt(sigma2/2); nobe = 0; Viterbi_init for i_frame=1:1:N_frame switch (bits_option) case {0}, bits=zeros(1,raw_bit_len); case {1}, bits=ones(1,raw_bit_len); case {2}, bits=randi(1,raw_bit_len,[0,1]); end encoding_bits = convolution_encoder(bits); interleaved=[]; for i=1:interleaving_num interleaved=[interleaved encoding_bits([i:interleaving_num:end])]; end temp_bit =[]; for tx_time=1:648 tx_bits=interleaved(1:8); interleaved(1:8)=[]; QAM16_symbol = QAM16_mod(tx_bits, 2); x(1,1) = QAM16_symbol(1); x(2,1) = QAM16_symbol(2); if rem(tx_time-1,81)==0 H = sq05(randn(2,2)+jrandn(2,2)); end y = Hx; if noise_option==1 noise = sqrt(sigma2/2)(randn(2,1)+j*randn(2,1)); y = y + noise; end W = inv(H'H+sigma2diag(ones(1,2)))H'; X_tilde = Wy; X_hat = QAM16_slicer(X_tilde, 2); temp_bit = [temp_bit QAM16_demapper(X_hat, 2)]; end deinterleaved=[]; for i=1:deinterleaving_num deinterleaved=[deinterleaved temp_bit([i:deinterleaving_num:end])]; end received_bit=Viterbi_decode(deinterleaved); for EC_dummy=1:1:raw_bit_len, if bits(EC_dummy)~=received_bit(EC_dummy), nobe=nobe+1; end if nobe>=nobe_target, break; end end if (nobe>=nobe_target) break; end end = BER(i_SNR) = nobe/((i_frame-1)*raw_bit_len+EC_dummy); fprintf('bits_option:%d,SNR:%d dB,BER:%1.4f\n',bits_option,SNRdB,BER(i_SNR)); end figure; semilogy(SNRdBs,BER); xlabel('SNR(dB)'); ylabel('BER'); title(['Bits_option:',num2str(bits_option)]); grid on; end将这段代码改为有噪声的情况

以下是添加噪声后的修改代码：

clear all; close all; clc;
tic
bits_options = [0,1,2];
noise_option = 1;
b = 4;
NT = 2;
SNRdBs =[0:2:20];
sq05=sqrt(0.5);
nobe_target = 500;
BER_target = 1e-3;
raw_bit_len = 2592-6;
interleaving_num = 72;
deinterleaving_num = 72;
N_frame = 1e8;

for i_bits=1:length(bits_options)
bits_option=bits_options(i_bits);
BER=zeros(size(SNRdBs));

for i_SNR=1:length(SNRdBs)
sig_power=NT;
SNRdB=SNRdBs(i_SNR);
sigma2=sig_power*10^(-SNRdB/10)+noise_option;
sigma1=sqrt(sigma2/2);
nobe = 0;
Viterbi_init

for i_frame=1:1:N_frame
switch (bits_option)
case {0}, bits=zeros(1,raw_bit_len);
case {1}, bits=ones(1,raw_bit_len);
case {2}, bits=randi(1,raw_bit_len,[0,1]);
end
encoding_bits = convolution_encoder(bits);

interleaved=[];
for i=1:interleaving_num
interleaved=[interleaved encoding_bits([i:interleaving_num:end])];
end

temp_bit =[];
for tx_time=1:648
tx_bits=interleaved(1:8);
interleaved(1:8)=[];

QAM16_symbol = QAM16_mod(tx_bits, 2);

x(1,1) = QAM16_symbol(1);
x(2,1) = QAM16_symbol(2);

if rem(tx_time-1,81)==0
H = sq05*(randn(2,2)+j*randn(2,2));
end

y = H*x;

if noise_option==1
noise = sqrt(sigma2/2)*(randn(2,1)+j*randn(2,1));
y = y + noise;
end

W = inv(H'*H+sigma2*diag(ones(1,2)))*H';
X_tilde = W*y;

X_hat = QAM16_slicer(X_tilde, 2);

temp_bit = [temp_bit QAM16_demapper(X_hat, 2)];
end

deinterleaved=[];
for i=1:deinterleaving_num
deinterleaved=[deinterleaved temp_bit([i:deinterleaving_num:end])];
end

received_bit=Viterbi_decode(deinterleaved);

for EC_dummy=1:1:raw_bit_len,
if bits(EC_dummy)~=received_bit(EC_dummy),
nobe=nobe+1;
end
if nobe>=nobe_target,
break;
end
end

if (nobe>=nobe_target)
break;
end
end
BER(i_SNR) = nobe/((i_frame-1)*raw_bit_len+EC_dummy);
fprintf('bits_option:%d,SNR:%d dB,BER:%1.4f\n',bits_option,SNRdB,BER(i_SNR));
end
figure;
semilogy(SNRdBs,BER);
xlabel('SNR(dB)');
ylabel('BER');
title(['Bits_option:',num2str(bits_option)]);
grid on;
end

clear all; close all; clc;ticits_option = 2;noise_option = 1;raw_bit_len = 2592-6;interleaving_num = 72;deinterleaving_num = 72;N_frame = 1e4;SNRdBs = [0:2:20];sq05 = sqrt(0.5);bits_options = [0, 1, 2]; % 三种bits-option情况obe_target = 500;BER_target = 1e-3;for i_bits = 1:length(bits_options) bits_option = bits_options(i_bits); BER = zeros(size(SNRdBs)); for i_SNR = 1:length(SNRdBs) sig_power = 1; SNRdB = SNRdBs(i_SNR); sigma2 = sig_power * 10^(-SNRdB/10); sigma = sqrt(sigma2/2); nobe = 0; for i_frame = 1:N_frame switch bits_option case 0 bits = zeros(1, raw_bit_len); case 1 bits = ones(1, raw_bit_len); case 2 bits = randi([0,1], 1, raw_bit_len); end encoding_bits = convolution_encoder(bits); interleaved = []; for i = 1:interleaving_num interleaved = [interleaved encoding_bits([i:interleaving_num:end])]; end temp_bit = []; for tx_time = 1:648 tx_bits = interleaved(1:8); interleaved(1:8) = []; QAM16_symbol = QAM16_mod(tx_bits, 2); x(1,1) = QAM16_symbol(1); x(2,1) = QAM16_symbol(2); if rem(tx_time - 1, 81) == 0 H = sq05 * (randn(2,2) + j * randn(2,2)); end y = H * x; if noise_option == 1 noise = sigma * (randn(2,1) + j * randn(2,1)); y = y + noise; end W = inv(H' * H + sigma2 * diag(ones(1,2))) * H'; K_tilde = W * y; x_hat = QAM16_slicer(K_tilde, 2); temp_bit = [temp_bit QAM16_demapper(x_hat, 2)]; end deinterleaved = []; for i = 1:deinterleaving_num deinterleaved = [deinterleaved temp_bit([i:deinterleaving_num:end])]; end received_bit = Viterbi_decode(deinterleaved); for EC_dummy = 1:1:raw_bit_len if nobe >= obe_target break; end if received_bit(EC_dummy) ~= bits(EC_dummy) nobe = nobe + 1; end end if nobe >= obe_target break; end end BER(i_SNR) = nobe / (i_frame * raw_bit_len); fprintf('bits-option: %d, SNR: %d dB, BER: %1.4f\n', bits_option, SNRdB, BER(i_SNR)); end figure; semilogy(SNRdBs, BER); xlabel('SNR (dB)'); ylabel('BER'); title(['Bits-Option: ', num2str(bits_option)]); grid on;end注释这段matlab代码

这是一段 Matlab 代码，以下是对其的注释：

% 清空所有变量、关闭所有图形窗口、清空命令行窗口、开始计时
clear all; close all; clc; tic

% 设置模拟参数
its_option = 2; % 暂时不知道其含义
noise_option = 1; % 噪声选项，1表示添加高斯白噪声，0表示不添加
raw_bit_len = 2592-6; % 原始比特长度，不包括尾部比特
interleaving_num = 72; % 扰码器长度
deinterleaving_num = 72; % 解扰码器长度
N_frame = 1e4; % 帧数
SNRdBs = [0:2:20]; % 信噪比范围
sq05 = sqrt(0.5); % sqrt(0.5)的值
bits_options = [0, 1, 2]; % 三种bits-option情况

obe_target = 500; % 最大误比特数目
BER_target = 1e-3; % 误比特率目标

% 循环处理三种bits-option情况
for i_bits = 1:length(bits_options)
    bits_option = bits_options(i_bits);
    BER = zeros(size(SNRdBs)); % 初始化误比特率
    for i_SNR = 1:length(SNRdBs)
        sig_power = 1; % 信号功率
        SNRdB = SNRdBs(i_SNR); % 当前信噪比
        sigma2 = sig_power * 10^(-SNRdB/10); % 方差
        sigma = sqrt(sigma2/2); % 标准差
        nobe = 0; % 误比特数目
        for i_frame = 1:N_frame
            switch bits_option
                case 0
                    bits = zeros(1, raw_bit_len);
                case 1
                    bits = ones(1, raw_bit_len);
                case 2
                    bits = randi([0,1], 1, raw_bit_len);
            end
            
            encoding_bits = convolution_encoder(bits); % 卷积编码
            
            % 扰码器
            interleaved = [];
            for i = 1:interleaving_num
                interleaved = [interleaved encoding_bits([i:interleaving_num:end])];
            end
            
            temp_bit = [];
            for tx_time = 1:648
                tx_bits = interleaved(1:8);
                interleaved(1:8) = [];
                QAM16_symbol = QAM16_mod(tx_bits, 2); % 16QAM调制
                x(1,1) = QAM16_symbol(1);
                x(2,1) = QAM16_symbol(2);
                if rem(tx_time - 1, 81) == 0 % 每81个时隙变化一次信道
                    H = sq05 * (randn(2,2) + j * randn(2,2));
                end
                
                y = H * x; % 信道传输
                if noise_option == 1 % 添加高斯白噪声
                    noise = sigma * (randn(2,1) + j * randn(2,1));
                    y = y + noise;
                end
                
                W = inv(H' * H + sigma2 * diag(ones(1,2))) * H'; % MMSE检测
                K_tilde = W * y;
                x_hat = QAM16_slicer(K_tilde, 2); % 16QAM解调
                temp_bit = [temp_bit QAM16_demapper(x_hat, 2)]; % 16QAM解调映射
            end
            
            % 解扰码器
            deinterleaved = [];
            for i = 1:deinterleaving_num
                deinterleaved = [deinterleaved temp_bit([i:deinterleaving_num:end])];
            end
            
            received_bit = Viterbi_decode(deinterleaved); % Viterbi译码
            
            % 统计误比特数目
            for EC_dummy = 1:1:raw_bit_len
                if nobe >= obe_target
                    break;
                end
                if received_bit(EC_dummy) ~= bits(EC_dummy)
                    nobe = nobe + 1;
                end
            end
            if nobe >= obe_target
                break;
            end
        end
        BER(i_SNR) = nobe / (i_frame * raw_bit_len); % 计算误比特率
        fprintf('bits-option: %d, SNR: %d dB, BER: %1.4f\n', bits_option, SNRdB, BER(i_SNR));
    end
    % 画图
    figure;
    semilogy(SNRdBs, BER);
    xlabel('SNR (dB)');
    ylabel('BER');
    title(['Bits-Option: ', num2str(bits_option)]);
    grid on;
end

% 结束计时
toc

注释解释：

- `%` 表示单行注释，用于注释代码的某一行。
- `clear all; close all; clc; tic` 表示清空所有变量、关闭所有图形窗口、清空命令行窗口、开始计时。
- `its_option = 2;` 表示设置模拟参数 `its_option`，但是没有注释说明其具体含义。
- `noise_option = 1;` 表示设置噪声选项，`1` 表示添加高斯白噪声，`0` 表示不添加。
- `raw_bit_len = 2592-6;` 表示设置原始比特长度，不包括尾部比特。
- `interleaving_num = 72;` 表示设置扰码器长度。
- `deinterleaving_num = 72;` 表示设置解扰码器长度。
- `N_frame = 1e4;` 表示设置帧数。
- `SNRdBs = [0:2:20];` 表示设置信噪比范围。
- `sq05 = sqrt(0.5);` 表示设置 sqrt(0.5) 的值。
- `bits_options = [0, 1, 2];` 表示设置三种 `bits-option` 情况。
- `obe_target = 500;` 表示设置最大误比特数目。
- `BER_target = 1e-3;` 表示设置误比特率目标。
- `for i_bits = 1:length(bits_options)` 开始循环处理三种 `bits-option` 情况。
- `switch bits_option` 根据 `bits-option` 的值选择不同的情况。
- `QAM16_symbol = QAM16_mod(tx_bits, 2);` 表示进行 16QAM 调制。
- `if rem(tx_time - 1, 81) == 0` 表示每 81 个时隙变化一次信道。
- `if noise_option == 1` 表示添加高斯白噪声。
- `x_hat = QAM16_slicer(K_tilde, 2);` 表示进行 16QAM 解调。
- `temp_bit = [temp_bit QAM16_demapper(x_hat, 2)];` 表示进行 16QAM 解调映射。
- `received_bit = Viterbi_decode(deinterleaved);` 表示进行 Viterbi 译码。
- `BER(i_SNR) = nobe / (i_frame * raw_bit_len);` 表示计算误比特率。
- `semilogy(SNRdBs, BER);` 表示画图，使用对数坐标轴。
- `toc` 表示结束计时。