CODEWITHSUNDEEP
java
visanio_learner
visanio_learner

Reputation: 413

to find the angle for cosine! vector products

I am looking for an answer to find an angle-alpha for cosine. 

cos(alpha)=RT(vector).R(vector)/(modulus)RT(vector).(modulus)R(vector)

then I should need to find the angle alpha.

public double dot1(double[] vectorA, double[] vectorB){
        double[] vecPro;
        vecPro = new double[2];
        vecPro[0] = vectorA[0]*vectorB[0];
        vecPro[1] = vectorA[1]*vectorB[1];
        return 0;
    }

this code is just an sample I did so far! for the dot product of RT(vector).R(vector). hmm is that correct that I did, because I am new to java language.

Upvotes: 0

Views: 208

Answers (2)

Stephen C
Stephen C

Reputation: 719576

It is hard to figure out what you are really asking, but the place to find implementations of the trigonometric functions like sine, cosine and tangent is the java.lang.Math class.

Upvotes: 1

nullpotent
nullpotent

Reputation: 9260

That doesn't calculate dot product. This does

public double dot1(double[] vectorA, double[] vectorB){ //if they're from R^2
        double[] vecPro = new double[2];
        vecPro[0] = vectorA[0]*vectorB[0];
        vecPro[1] = vectorA[1]*vectorB[1]; 
        //you did fine up to here
        //But, you should return the result (sum of components products) @see wiki link
        //0 surely isn't the result you want for two arbitrary vectors
        return vecPro[0] + vecPro[1]; 
}

Upvotes: 2

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