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11 lines
558 B
C++
11 lines
558 B
C++
Matrix2d m; m << 1,2,3,4;
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Matrix2d n;
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n = (m*m).lazy(); // if we did "n = m*m;" then m*m would first be evaluated into
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// a temporary, because the Product expression has the EvalBeforeAssigningBit.
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// This temporary would then be copied into n. Introducing this temporary is
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// useless here and wastes time. Doing "n = (m*m).lazy();" evaluates m*m directly
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// into n, which is faster. But, beware! This is only correct because m and n
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// are two distinct matrices. Doing "m = (m*m).lazy();" would not produce the
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// expected result.
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cout << n << endl;
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