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14417: THE 'EXPONENTIATION' OPERATION (offset 6)
 The address of this routine is found in the table of addresses. It is called indirectly via fp_calc_2, and the routine at sqr continues here. This subroutine performs the binary operation of raising the first number, X, to the power of the second number, Y. The subroutine treats the result X**Y as being equivalent to EXP (Y*LN X). It returns this value unless X is zero, in which case it returns 1 if Y is also zero (0**0=1), returns zero if Y is positive, and reports arithmetic overflow if Y is negative. to_power 14417 RST 40 X, Y 14418 DEFB 1 exchange: Y, X 14419 DEFB 49 duplicate: Y, X, X 14420 DEFB 48 f_not: Y, X, (1/0) 14421 DEFB 0 jump_true to XIS0: Y, X 14422 DEFB 7 The jump is made if X=0, otherwise EXP (Y*LN X) is formed. 14423 DEFB 37 ln: Y, LN X Giving report A if X is negative. 14424 DEFB 4 multiply: Y*LN X 14425 DEFB 56 end_calc 14426 JP exp Exit via exp to form EXP (Y*LN X). The value of X is zero so consider the three possible cases involved. XIS0 14429 DEFB 2 delete: Y 14430 DEFB 49 duplicate: Y, Y 14431 DEFB 48 f_not: Y, (1/0) 14432 DEFB 0 jump_true to ONE: Y 14433 DEFB 9 The jump is made if X=0 and Y=0, otherwise proceed. 14434 DEFB 160 stk_zero: Y, 0 14435 DEFB 1 exchange: 0, Y 14436 DEFB 55 greater_0: 0, (1/0) 14437 DEFB 0 jump_true to LAST: 0 14438 DEFB 6 The jump is made if X=0 and Y is positive, otherwise proceed. 14439 DEFB 161 stk_one: 0, 1 14440 DEFB 1 exchange: 1, 0 14441 DEFB 5 division: Exit via division as dividing by zero gives 'arithmetic overflow'. The result is to be 1 for the operation. ONE 14442 DEFB 2 delete: - 14443 DEFB 161 stk_one: 1 Now return with the 'last value' on the stack being 0**Y. LAST 14444 DEFB 56 end_calc: (1/0) 14445 RET Finished: 'last value' is 0 or 1.
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