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SAS Tip of the Month
February 2007

This month is a quick look at the trigonometric functions available in SAS.

    Function  Trigonometric  Inverse  Hyperbolic
    --------------------------------------------
    Sine           SIN        ARSIN      SINH
    Cosine         COS        ARCOS      COSH
    Tangent        TAN        ATAN       TANH

Note that all angles that are entered using the trigonometric functions are in radians, i.e. if the angle is in degrees then this value must be multiplied by PI/180 before using the function.

The following example demonstrates the use of the SIN function and returning its inverse:

    data _null_;
      pi=constant('PI');
      angle=30*PI/180;
      sinx=sin(angle);
      arsinx=arsin(sinx)*180/pi;
      put angle= sinx= arsinx= pi=;
    run;

produces the output in the log

    angle=0.5235987756 sinx=0.5 arsinx=30 pi=3.1415926536

Note the use of the CONSTANT function - this function accesses certain mathematical constants, including PI, that are set within SAS.

Before SAS version 8 the constant for PI did not exist so alternates were used to set a value for PI, namely setting PI to a value say 3.14159, or if more accuracy was needed setting the value to the result of ARCOS(-1).