小编JmJ*_*JmJ的帖子

我有一个矩阵A和一个向量x:

A 是一个50x30矩阵

x 是1x30向量

我想乘A用x,但每当我尝试z = A * x,我得到的错误Inner matrix dimensions must agree.还有,可以肯定用相同数量的列的矩阵尺寸不同意吗？

我很困惑为什么这样做:

A = rand(2,2);
x = [1;2];
A * x

然而,这不起作用:

A = rand(2,2);
x = 1:2;
A * x

I understand what the error is saying and I have been able to fix it, but I was hoping someone could provide some clarification on why it's happening now and why it isn't happening in other areas of my app, as well as why a function and a ternary with essentially the same type signature produce different results.

I wanted to display a basic error message in the following style:

{!!error.message && (
  <Text>{error.message}</Text>
)}

But it gives the error …

只是想知道当我在C中使用错误的格式说明符时会发生什么？

例如:

x = 'A';
printf("%c\n", x);
printf("%d\n", x);

x = 65;
printf("%c\n", x);
printf("%d\n", x);

x = 128;
printf("%d\n", x);

我刚刚重新安装了 WebStorm，之前在 JSX 字段中按 Tab 键时创建了打开和关闭标签，但现在只创建了一个自封闭标签。

JSX 的 Emmet 设置仅显示开/关切换。我怎样才能解决这个问题？

之前：

制表符 + Component=<Component></Component>

现在：

制表符 + Component=<Component/>

我正在尝试使用Swing在Java中创建一个简单的计算器,并且我按以下方式创建了我的按钮:

//Our number keypad
public static JPanel numbers(){

    //our panel to return
    JPanel panel = new JPanel();

    //Create and add 3x4 grid layout to panel
    GridLayout gl = new GridLayout(3, 4);
    panel.setLayout(gl);

    //For creating and adding buttons to panel
    for(int i = 0; i < 10; i++){

        //Create a new button where the name is the value of i
        String name = "" + i + "";
        JButton button = new JButton(name);

        //add action listener
        button.addActionListener(handler);

        //Add button to panel …

我试图在我的main createFile方法中从OpenFile类中调用我的方法,但我不断收到错误,说我不能从静态上下文中调用非静态变量.

我确实尝试OpenFile of = new OpenFile();在我的main方法中调用,但是这没有用,所以我现在声明OpenFile我的main方法上面工作正常,但是每次我尝试使用OpenFiles方法之一时我都会得到相同的错误.

我尝试过使用一些东西,static但这只会导致我的IDE显示错误的sym类型错误,我认为这是由引起其他错误的任何原因引起的.

这是createFile来自OpenFile:

public class OpenFile {

    private Formatter file;

    public void createFile() throws FileNotFoundException{

        try{
            file = new Formatter("test.txt");
        } catch(Exception e) {
            System.out.println("Error creating file.");
    }
    }

这是我的主要方法:

OpenFile of = new OpenFile();

public static void main(String[] args) {
    // TODO code application logic here

    of.createFile();
    intro();
    createAndShowRibbon();
    createAndShowNormalUI();

}

它与Formatter有关吗？我以前从未使用过它.

谢谢.