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y. T. R. S. x. ′. ′. ′. R. S. T. 4.3 Matrix of Linear Transformations. Example 2. Find a matrix B that represents a linear transformation from T(f) = f ’ + f ” from P 2 to P 2 with respect to the standard basis Β =(1, x, x 2 ). Example 2. T(f) = f ’ + f ”. Similar matrices.
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y T R S x ′ ′ ′ R S T 4.3 Matrix of Linear Transformations
Example 2 Find a matrix B that represents a linear transformation from T(f) = f’ + f” from P2 to P2 with respect to the standard basis Β =(1, x, x2)
Example 2 T(f) = f’ + f”
Similar matrices Had we used a different basis, we could describe this same transformation using that basis. Two matrices that describe the same transformation with regard to a different basis are called similar matrices and are related by the formula SAS-1= B In this formula A is similar to B
An Application Write a matrix that will find the 2nd derivative of a polynomial of degree 3 or lower. Use this matrix to find the 2nd derivative of x3 + 2x2 + 4x +1
Application solution Start with a basis: 1,x,x2,x3 Find the second derivative of each of the elements of the basis. Write the answer in terms of coordinates of the basis. 0 0 2 0 0 0 0 6 0 0 0 0 0 0 0 0
Application part B Use matrix multiplication to find the second derivative of x3 + 2x2 + 4x +1
Application part B Multiply the coordinate matrix times the matrix that represents x3 + 2x2 + 4x +1 in terms of our basis 1,x,x2,x3 0 0 2 0 1 4 0 0 0 6 4 = 6 0 0 0 0 2 0 0 0 0 0 1 0 y”=6x + 4
Solution to 3b Because there is an invertible matrix that describes the transformation T we call T an isomorphism
Problem 6 Find the matrix of transformation
6 solution What does this mean? If I had the vector <1,0,1> as my x it means that I had 1 of the first element, 0 of the second and 1 of the 3rd Or the matrix 1 1 and ran it through the transformation I would get 0 1 The matrix 1 3 using the answer from above as A <1,01> as x 0 3 yields <1,0,3> which are coordinates for the answer [ ] [ ]
Homework p.181 1-19 odd lim sin(x) = 6 n --> ∞ n Proof: cancel the n in the numerator and denominator.
Example 1 Express using coordinates
Why are similar matrices related by B = S-1AS Note: start at the lower left hand corner of the diagram and move to the upper right hand corner by each direction