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6.8.5 Yacas Language Mode

The d Y (calc-yacas-language) command selects the conventions of Yacas, a free computer algebra system. While the operators and functions in Yacas are similar to those of Calc, the names of built-in functions in Yacas are capitalized. The Calc formula ‘sin(2 x)’, for example, is entered and displayed ‘Sin(2 x)’ in Yacas mode, and ‘arcsin(x^2)’ is ‘ArcSin(x^2)’ in Yacas mode. Complex numbers are written are written ‘3 + 4 I’. The standard special constants are written Pi, E, I, GoldenRatio and Gamma. Infinity represents both inf and uinf, and Undefined represents nan.

Certain operators on functions, such as D for differentiation and Integrate for integration, take a prefix form in Yacas. For example, the derivative of ‘e^x sin(x) can be computed with ‘D(x) Exp(x)*Sin(x).

Other notable differences between Yacas and standard Calc expressions are that vectors and matrices use curly braces in Yacas, and subscripts use square brackets. If, for example, ‘A’ represents the list ‘{a,2,c,4}’, then ‘A[3]’ would equal ‘c’.