Java//数组//乘法//For循环；

目标：使用旋转矩阵生成旋转

private double[][] rotateX = {{1.00,0.00,0.00},{0.00,Math.cos(theta),Math.sin(-theta)},{0.00,Math.sin(theta),Math.cos(theta)}};   // Rotation matrice for x axis;

问题定义：输出与预期不匹配

预期输出：

newX = 3
newY = -2.236 
newZ = -0.002
// Checked in MathCAD;

public class Test2 {
private double[] target = {3.00,1.00,2.00};        // target data for matrix multiplication;
private double[] product = {0.00,0.00,0.00};       // product of the for-loop;

private double theta = Math.toRadians(90.00);      // Rotation angle;

private double[][] rotateX = {{1.00,0.00,0.00},
        {0.00,Math.cos(theta),Math.sin(-theta)},
        {0.00,Math.sin(theta),Math.cos(theta)}};   // Rotation matrice for x axis;

private void rotateAroundX(){
    double temp;                                  // temp. data storage;

    double newX = 0.00;                           // new x after for-loop;
    double newY = 0.00;                           // new y after for-loop;
    double newZ = 0.00;                           // new z after for-loop;

    for(int i = 0; i < rotateX.length ; i ++){          // check how many items are stored in the matrix;
        for(int j = 0; j < rotateX[i].length; j++){     // check how many elements are stored in each item;

            temp = rotateX[i][j] * target[j];           // store product of the multiplication in temp;

            if(i == 0){
                newX += temp;                           // if i index is 0 finalize matrix multiplication and set newX; Ex. 1 row of rotateX - (1.00*3.00 + 0.00*1.00 + 0.00*2.00); 
            }
            if(i == 1){                                 // if i index is 1 finalize matrix multiplication and set newY;
                newY += temp;
            }
            if(i == 2){                                 // if i index is 2 finalize matrix multiplication and set newZ;
                newZ += temp;
            }
        }
    }

    this.product[0] = newX;                             // Add newX to product;
    this.product[1] = newY;                             // Add newY to product;
    this.product[2] = newZ;                             // Add newZ to product;                 

}

public void sart(){
    rotateAroundX();                   // run test-case;

    for (double e : product){
        System.out.println(e);         // output the product information;
    }
}
}

产生的输出：

newX = 3.00
newY =-2.00
newZ = 1.0000000000000002

应用的代码：

newX = 3
newY = -2.236 
newZ = -0.002
// Checked in MathCAD;

public class Test2 {
private double[] target = {3.00,1.00,2.00};        // target data for matrix multiplication;
private double[] product = {0.00,0.00,0.00};       // product of the for-loop;

private double theta = Math.toRadians(90.00);      // Rotation angle;

private double[][] rotateX = {{1.00,0.00,0.00},
        {0.00,Math.cos(theta),Math.sin(-theta)},
        {0.00,Math.sin(theta),Math.cos(theta)}};   // Rotation matrice for x axis;

private void rotateAroundX(){
    double temp;                                  // temp. data storage;

    double newX = 0.00;                           // new x after for-loop;
    double newY = 0.00;                           // new y after for-loop;
    double newZ = 0.00;                           // new z after for-loop;

    for(int i = 0; i < rotateX.length ; i ++){          // check how many items are stored in the matrix;
        for(int j = 0; j < rotateX[i].length; j++){     // check how many elements are stored in each item;

            temp = rotateX[i][j] * target[j];           // store product of the multiplication in temp;

            if(i == 0){
                newX += temp;                           // if i index is 0 finalize matrix multiplication and set newX; Ex. 1 row of rotateX - (1.00*3.00 + 0.00*1.00 + 0.00*2.00); 
            }
            if(i == 1){                                 // if i index is 1 finalize matrix multiplication and set newY;
                newY += temp;
            }
            if(i == 2){                                 // if i index is 2 finalize matrix multiplication and set newZ;
                newZ += temp;
            }
        }
    }

    this.product[0] = newX;                             // Add newX to product;
    this.product[1] = newY;                             // Add newY to product;
    this.product[2] = newZ;                             // Add newZ to product;                 

}

public void sart(){
    rotateAroundX();                   // run test-case;

    for (double e : product){
        System.out.println(e);         // output the product information;
    }
}
}

公共类Test2{
private double[]target={3.00,1.00,2.00}；//矩阵乘法的目标数据；
私有双[]乘积={0.00,0.00,0.00}；//for循环的乘积；
private double theta=Math.toRadians（90.00）；//旋转角度；
私人双[]旋转={{1.00,0.00,0.00}，
{0.00，Math.cos（θ），Math.sin（-θ）}，
{0.00，Math.sin（θ），Math.cos（θ）}；//x轴的旋转矩阵；
私有void rotateAroundX（）{
双温度；//温度数据存储；
double newX=0.00；//for循环后的新x；
double newY=0.00；//在for循环之后新y；
double newZ=0.00；//for循环后的新z；
对于（int i=0；i

我认为答案有点奇怪，但很简单：您预期的输出是错误的。在我看来，您生成的输出似乎是正确的。

您使用的是弧度，而在预期输出中，您使用的是度

改变

private double theta = Math.toRadians(90.00);

致：

---

提供您期望的输出。

当您使用调试器逐步完成此操作时，您发现了什么？@OliCharlesworth-没有任何东西流程如预期的那样，但是输出与基于MathCAD结果的我所期望的不同。这让我感到困惑，因为该文档说明cos（）/sin（）的输入/tan（）函数必须以弧度为单位；也许你的预期输出计算不正确，因为你是对的，数学三角函数使用弧度，我只是尝试了一下。您是否认为用于预期输出的方法使用度，但实际上它使用弧度？我已经阅读了MathCAD的文档@埃德加波达：你说得对。问题在于用于计算预期结果的方法。请加上你的答案，我将投票选出正确答案。