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functions:llacos [2014-01-03 10:18 SLT] sei created |
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| ===== Function: llAcos ===== | ===== Function: llAcos ===== | ||
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| </code> | </code> | ||
| - | Return the inverse cosine of the argument, in radians. The inverse cosine is the angle whose cosine is the given argument. | + | Return the inverse cosine of the argument, in radians. The inverse cosine (also known as arccosine) is the angle whose cosine is the given argument. |
| ===== Parameters ===== | ===== Parameters ===== | ||
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| Number whose inverse cosine is to be found. | Number whose inverse cosine is to be found. | ||
| - | ===== Result ===== | + | ===== Return value ===== |
| - | [[types/Float]] number with the inverse cosine of the argument. | + | $lty[Float] number with the angle in radians that is the inverse cosine of the argument. |
| ===== Notes ===== | ===== Notes ===== | ||
| - | * The range must be between -1 and 1, because the cosine of any angle can't be outside that range. | + | * The range of $prm[arg] must be between -1 and 1, because the cosine of any angle can't be outside that range. |
| + | * The result is always between 0 and $lct[PI], or $nan if the argument is out of the valid range. | ||
| ===== Short examples ===== | ===== Short examples ===== | ||
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| angle = llAcos(-1); // Sets angle to PI, because the cosine of PI is -1. | angle = llAcos(-1); // Sets angle to PI, because the cosine of PI is -1. | ||
| angle = llAcos(0.31); // Sets angle to approximately 1.255603 (the cosine of that is 0.31) | angle = llAcos(0.31); // Sets angle to approximately 1.255603 (the cosine of that is 0.31) | ||
| - | angle = llAcos(2); // Sets angle to NaN (Not a Number) because there's no number whose cosine is 2. | + | |
| + | angle = llAcos(2); // Under Mono, sets angle to NaN (Not a Number), | ||
| + | // because there's no number whose cosine is 2. | ||
| + | // Crashes with a math error under LSO. | ||
| </code> | </code> | ||
| - | ===== See also ===== | + | ===== Complete examples ===== |
| - | === Related trigonometric functions === | + | A $lty[rotation] can be expressed by an axis and an angle. This example illustrates how to use $fn[llAcos] to obtain the angle component of a rotation, assumed it's normalized (most LSL functions return normalized rotations). If the rotation is not guaranteed to be normalized, use $lfn[llRot2Angle] instead. |
| - | * [[llCos]] | + | |
| + | <file lsl2 llAcos-example.lsl> | ||
| + | default | ||
| + | { | ||
| + | state_entry() | ||
| + | { | ||
| + | rotation rot = llGetLocalRot(); | ||
| + | llOwnerSay("The angle of rotation of this prim is " + (string)(2*llAcos(rot.s)) + " radians."); | ||
| + | } | ||
| + | } | ||
| + | </file> | ||
| + | |||
| + | ===== See also ===== | ||
| - | === Other trigonometric functions === | + | * $lfn[llCos] calculates the cosine of the argument. |
| - | * [[llAsin]] | + | * $lfn[llAsin] calculates the inverse sine of the argument. |
| - | * [[llSin]] | + | * $lfn[llSin] calculates the sine of the argument. |
| - | * [[llAtan2]] | + | * $lfn[llAtan2] calculates the angle of a 2D vector. |
| - | * [[llTan]] | + | * $lfn[llTan] calculates the tangent of the argument. |
| + | * Other $lfn[math/] functions. | ||