Routines |
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Used by the routine at to_power.
The address of this routine is found in the table of addresses. It is called indirectly via fp_calc_2.
This subroutine handles the function EXP X and is the first of four routines that use the series generator to produce Chebyshev polynomials.
The approximation to EXP X is found as follows:
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exp | 14020 | RST 40 | X | |
Perform step i.
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14021 | DEFB 61 | re_stack: X (in full floating-point form) | ||
14022 | DEFB 52 | stk_data: X, 1/LN 2 | ||
14023 | DEFB 241,56,170,59,41 | |||
14028 | DEFB 4 | multiply: X/LN 2=Y | ||
Perform step ii.
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14029 | DEFB 49 | duplicate: Y, Y | ||
14030 | DEFB 39 | int: Y, INT Y=N | ||
14031 | DEFB 195 | st_mem_3: Y, N (mem-3 holds N) | ||
Perform step iii.
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14032 | DEFB 3 | subtract: Y-N=W | ||
Perform step iv.
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14033 | DEFB 49 | duplicate: W, W | ||
14034 | DEFB 15 | addition: 2*W | ||
14035 | DEFB 161 | stk_one: 2*W, 1 | ||
14036 | DEFB 3 | subtract: 2*W-1=Z | ||
Perform step v, passing to the series generator the parameter '8' and the eight constants required.
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14037 | DEFB 136 | series_08: Z | ||
14038 | DEFB 19,54 | |||
14040 | DEFB 88,101,102 | |||
14043 | DEFB 157,120,101,64 | |||
14047 | DEFB 162,96,50,201 | |||
14051 | DEFB 231,33,247,175,36 | |||
14056 | DEFB 235,47,176,176,20 | |||
14061 | DEFB 238,126,187,148,88 | |||
14066 | DEFB 241,58,126,248,207 | |||
At the end of the last loop the 'last value' is 2**W.
Perform step vi.
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14071 | DEFB 227 | get_mem_3: 2**W, N | ||
14072 | DEFB 56 | end_calc | ||
14073 | CALL FP_TO_A | The absolute value of N mod 256 is put into the A register. | ||
14076 | JR NZ,N_NEGTV | Jump forward if N was negative. | ||
14078 | JR C,REPORT_6_2 | Error if ABS N>255. | ||
14080 | ADD A,(HL) | Now add ABS N to the exponent. | ||
14081 | JR NC,RESULT_OK | Jump unless e>255. | ||
Report 6 - Number too big.
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REPORT_6_2 | 14083 | RST 8 | Call the error handling routine. | |
14084 | DEFB 5 | |||
N_NEGTV | 14085 | JR C,RSLT_ZERO | The result is to be zero if N<-255. | |
14087 | SUB (HL) | Subtract ABS N from the exponent as N was negative. | ||
14088 | JR NC,RSLT_ZERO | Zero result if e less than zero. | ||
14090 | NEG | Minus e is changed to e. | ||
RESULT_OK | 14092 | LD (HL),A | The exponent, e, is entered. | |
14093 | RET | Finished: 'last value' is EXP X. | ||
RSLT_ZERO | 14094 | RST 40 | Use the calculator to make the 'last value' zero. | |
14095 | DEFB 2 | delete (the stack is now empty) | ||
14096 | DEFB 160 | stk_zero: 0 | ||
14097 | DEFB 56 | end_calc | ||
14098 | RET | Finished, with EXP X=0. |
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