Trigonometric functions: Difference between revisions
add ZX Spectrum
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Kinitawowi (talk | contribs) (add ZX Spectrum) |
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(1.0).atan().toDeg() //-->45
etc</lang>
=={{header|ZX Spectrum Basic}}==
The ZX Spectrum ROM only calculates sine and arctangent directly (via Chebyshev polynomials), and uses internal functions of these (and the square root) to generate the other functions. In particular, arcsin x is calculated as arctan ( x / ( sqrt ( 1 - x * x ) ) + 1 ) / 2, which is why some of these functions are legendarily slow.
<lang zxbasic>10 DEF FN d(a)=a*PI/180:REM convert degrees to radians; all ZX Spectrum trig calculations are done in radians
20 DEF FN i(r)=180*r/PI:REM convert radians to degrees for inverse functions
30 LET d=45
40 LET r=PI/4
50 PRINT SIN r,SIN FN d(d)
60 PRINT COS r,COS FN d(d)
70 PRINT TAN r,TAN FN d(d)
80 PRINT
90 LET d=.5
110 PRINT ASN d,FN i(ASN d)
120 PRINT ACS d,FN i(ACS d)
130 PRINT ATN d,FN i(ATN d)</lang>
{{out}}
<pre>
0.70710678 0.70710678
0.70710678 0.70710678
1 1
0.52359878 30
1.0471976 60
0.46364761 26.565051
0 OK, 130:1
</pre>
{{omit from|Batch File|No access to advanced math.}}
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