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Instruction general - FCOS—Cosine

Calculates the cosine of the source operand in register ST(0) and stores the result in ST(0). The source operand must be given in radians and must be within the range -2^63 to +2^63. If the source operand is outside the acceptable range, the C2 flag in the FPU status word is set, and the value in register ST(0) remains unchanged. The instruction does not raise an exception when the source operand is out of range. It is up to the program to check the C2 flag for out-of-range conditions. Source values outside the range -2^63 to +2^63 can be reduced to the range of the instruction by subtracting an appropriate integer multiple of 2pi or by using the FPREM instruction with a divisor of 2pi.