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Table 4 Characters & strings allowed within OGIP datasets to denote mathematical operations

              String     Meaning

                str1 * str2   Multiplication (see also Section 3.1.1)
                str1 /str2    Division (see also Section 3.1.2)
                str1**(y)     Raised to the power y (see also Section 3.1.3)
                log(str1)     Common Logarithm (to base 10)
                ln(str1)      Natural Logarithm
                exp(str1)     Exponential (expstr1>
                sqrt(str1)    Square root
                sin(str1)     Sine
                cos(str1)     Cosine
                tan(str1)     Tangent
                asin(str1)    Arc Sine
                acos(str1)    ArcCosine
                atan(str1)    Arc Tangent
                sinh(str1)    Hyperbolic Sine
                cosh(str1)    Hyperbolic Cosine
                tanh(str1)    Hyperbolic Tangent