Having trouble with the math node, taking the result of a cos() function to a power. Anyone else seen this? I've attached a minimal patch that shows the bug.
In a fractional exponent, the numerator is the power to which the number should be taken and the denominator is the root which should be taken. For example, 125 means "take 125 to the fourth power and take the cube root of the result" or "take the cube root of 125 and then take the result to the fourth power." Order does not matter when evaluating exponents--it is usually easier to take the root first, and then take the power.
Since we cannot take the even root of a negative number, we cannot take a negative number to a fractional power if the denominator of the exponent is even. cos(1.5*pi/2) = -0.707 and 10.3 is 103/10 (even denominator) My calculator gives “error” as the answer.