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# all functions - l

 l2ll ``` z = l2ll(x) convert 2-by-dims 32 bit integer X to 64 bit integer (only works if sizeof(long)=8) interpreted function, defined at i/idlsave.i line 299 ```

 l_frame ``` l_frame struct l_frame { float x_min, x_max, y_min, y_max; } structure, defined at i/testb.i line 884 ```

 lagrange ``` lagrange interpreted function, defined at i/demo3.i line 78 ```

 laguerre ``` laguerre(a,x) Given the coefficients a(1:m+1) of the m'th degree complex polynomial Sum(a(i)*x^(i-1)) and a guess x, returns a root. See Numerical Recipes (Press, et. al., Cambridge Univ. Press 1988), section 9.5. interpreted function, defined at i/zroots.i line 70 ```

 laplacian ``` laplacian interpreted function, defined at i/demo2.i line 158 ```

 lbs ``` lbs returns linear b spline in 1,2,3,4 D EXAMPLE > lbs([-1.,-0.5,0,0.5,1]) [0,0.5,1,0.5,0] interpreted function, defined at contrib/histon.i line 6 ``` SEE ALSO:

 lcm ``` lcm(a,b) returns the LCM (least common multiple) of A and B, which must be one of the integer data types. A and B may be conformable arrays; the semantics of the lcm call are the same as any other binary operation. The absolute values of A and B are taken before the operation commences; if either A or B is 0, the return value will be 0. interpreted function, defined at i/gcd.i line 47 ``` SEE ALSO: gcd,   is_prime,   factorize

 ldist ``` ldist(z,q0=,lambda0=) Compute the term to integrate to compute the luminosity distance. z can be a VECTOR of values. KEYWORDS: q0 : Deceleration parameter,numeric scalar -a*(a'')/(a')^2 (Omega_m/2-lambda0) lambda0 : Cosmological constant, normalized to th closure density. interpreted function, defined at contrib/cosmo.i line 104 ``` SEE ALSO: lumdist

 legal ``` legal Prints the legal details of Yorick's copyright, licensing, and lack of warranty. interpreted function, defined at i0/std.i line 88 ``` SEE ALSO: copyright,   warranty

 legndr ``` legndr(l,m, x) return the associated Legendre function Plm(x). The X may be an array (-1<=x<=1), but L and M (0<=M<=L) must be scalar values. For m=0, these are the Legendre polynomials Pl(x). Relation of Plm(x) to Pl(x): Plm(x) = (-1)^m (1-x^2)^(m/2) d^m/dx^m(Pl(x)) Relation of Plm(x) to spherical harmonics Ylm: Ylm(theta,phi)= sqrt((2*l+1)(l-m)!/(4*pi*(l+m)!)) * Plm(cos(theta)) * exp(1i*m*phi) interpreted function, defined at i/legndr.i line 12 ``` SEE ALSO: ylm_coef

 library ``` library print the Y_SITE/i/README file at the terminal. interpreted function, defined at i0/std.i line 1667 ```

 light3 ``` light3, ambient=a_level, diffuse=d_level, specular=s_level, spower=n, sdir=xyz Sets lighting properties for 3D shading effects. A surface will be shaded according to its to its orientation relative to the viewing direction. The ambient level A_LEVEL is a light level (arbitrary units) that is added to every surface independent of its orientation. The diffuse level D_LEVEL is a light level which is proportional to cos(theta), where theta is the angle between the surface normal and the viewing direction, so that surfaces directly facing the viewer are bright, while surfaces viewed edge on are unlit (and surfaces facing away, if drawn, are shaded as if they faced the viewer). The specular level S_LEVEL is a light level proportional to a high power spower=N of 1+cos(alpha), where alpha is the angle between the specular reflection angle and the viewing direction. The light source for the calculation of alpha lies in the direction XYZ (a 3 element vector) in the viewer's coordinate system at infinite distance. You can have ns light sources by making S_LEVEL, N, and XYZ (or any combination) be vectors of length ns (3-by-ns in the case of XYZ). (See source code for specular_hook function definition if powers of 1+cos(alpha) aren't good enough for you.) With no arguments, return to the default lighting. EXAMPLES: light3, diffuse=.1, specular=1., sdir=[0,0,-1] (dramatic "tail lighting" effect) light3, diffuse=.5, specular=1., sdir=[1,.5,1] (classic "over your right shoulder" lighting) light3, ambient=.1,diffuse=.1,specular=1., sdir=[[0,0,-1],[1,.5,1]],spower=[4,2] (two light sources combining previous effects) interpreted function, defined at i/pl3d.i line 262 ``` SEE ALSO: rot3,   save3,   restore3

 lightwf ``` lightwf, cmax Sets the cmax= parameter interactively, assuming the current 3D display list contains the result of a previous plwf call. This changes the color of the brightest surface in the picture. The darkest surface color can be controlled using the ambient= keyword to light3. interpreted function, defined at i/plwf.i line 131 ``` SEE ALSO: plwf,   light3

 limit3 ``` limit3, xmin,xmax, ymin,ymax or limit3, xmin,xmax, ymin,ymax, zmin,zmax Set the 3D axis limits for use with the cage. Use keyword aspect=[ax,ay,az] to set the aspect ratios of the cage to ax:ay:az -- that is, the ratios of the lengths of the cage axes will become ax:ay:az. interpreted function, defined at i/pl3d.i line 181 ``` SEE ALSO: cage3,   range3,   plwf,   plwf,   orient3

 limits ``` limits or limits, xmin, xmax, ymin, ymax, square=0/1, nice=0/1, restrict=0/1 or old_limits= limits() or limits, old_limits In the first form, restores all four plot limits to extreme values. In the second form, sets the plot limits in the current coordinate system to XMIN, XMAX, YMIN, YMAX, which may be nil or omitted to leave the corresponding limit unchanged, a number to fix the corresponding limit to a specified value, or the string "e" to make the corresponding limit take on the extreme value of the currently displayed data. If present, the square keyword determines whether limits marked as extreme values will be adjusted to force the x and y scales to be equal (square=1) or not (square=0, the default). If present, the nice keyword determines whether limits will be adjusted to nice values (nice=1) or not (nice=0, the default). There is a subtlety in the meaning of "extreme value" when one or both of the limits on the OPPOSITE axis have fixed values -- does the "extreme value" of the data include points which will not be plotted because their other coordinate lies outside the fixed limit on the opposite axis (restrict=0, the default), or not (restrict=1)? If called as a function, limits returns an array of 5 doubles; OLD_LIMITS(1:4) are the current xmin, xmax, ymin, and ymax, and int(OLD_LIMITS(5)) is a set of flags indicating extreme values and the square, nice, restrict, and log flags. In the fourth form, OLD_LIMITS is as returned by a previous limits call, to restore the limits to a previous state. In an X window, the limits may also be adjusted interactively with the mouse. Drag left to zoom in and pan (click left to zoom in on a point without moving it), drag middle to pan, and click (and drag) right to zoom out (and pan). If you click just above or below the plot, these operations will be restricted to the x-axis; if you click just to the left or right, the operations are restricted to the y-axis. A shift-left click, drag, and release will expand the box you dragged over to fill the plot (other popular software zooms with this paradigm). If the rubber band box is not visible with shift-left zooming, try shift-middle or shift-right for alternate XOR masks. Such mouse-set limits are equivalent to a limits command specifying all four limits EXCEPT that the unzoom command can revert to the limits before a series of mouse zooms and pans. The limits you set using the limits or range functions carry over to the next plot -- that is, an fma operation does NOT reset the limits to extreme values. builtin function, documented at i0/graph.i line 715 ``` SEE ALSO: plsys,   range,   logxy,   zoom_factor,   unzoom,   plg,   viewport

 lissajous ``` lissajous runs the Yorick equivalent of an old graphics performance test used to compare PLAN, ALMA, and Basis with LTSS TMDS graphics. interpreted function, defined at i/testg.i line 185 ``` SEE ALSO: testg,   grtest

 ln_gamma ``` ln_gamma(z) returns natural log of the gamma function. Error is less than 1e-13 for real part of z>=1. Use lngamma if you know that all z>=1, or if you don't care much about accuracy for z<1. interpreted function, defined at i/gamma.i line 16 ``` SEE ALSO: lngamma,   bico,   beta

 lngamma ``` lngamma(x) returns natural log of the gamma function. Error is less than 1e-13 for real part of x>=1. Use ln_gamma if some x<1. interpreted function, defined at i/gamma.i line 37 ``` SEE ALSO: ln_gamma,   bico,   beta

 log ``` log(x) returns the natural logarithm of its argument (inverse of exp). builtin function, documented at i0/std.i line 613 ``` SEE ALSO: log1p,   log10,   exp,   asinh,   acosh,   atanh

 log10 ``` log10(x) returns the base 10 logarithm of its argument (inverse of 10^x). builtin function, documented at i0/std.i line 619 ``` SEE ALSO: log,   exp,   asinh,   acosh,   atanh

 log1p ``` log1p(x) return log(1+X) accurate to machine precision (even for X<<1) from Goldberg, ACM Computing Surveys, Vol 23, No 1, March 1991, apparently originally from HP-15C Advanced Functions Handbook interpreted function, defined at i0/std.i line 637 ``` SEE ALSO: expm1,   log1p

 logxy ``` logxy, xflag, yflag sets the linear/log axis scaling flags for the current coordinate system. XFLAG and YFLAG may be nil or omitted to leave the corresponding axis scaling unchanged, 0 to select linear scaling, or 1 to select log scaling. builtin function, documented at i0/graph.i line 785 ``` SEE ALSO: plsys,   limits,   range,   plg,   gridxy

 lon_lat ``` lon_lat interpreted function, defined at i/kepler.i line 474 ```

 lon_subtract ``` lon_subtract interpreted function, defined at i/kepler.i line 481 ```

 lookup_akap ``` lookup_akap interpreted function, defined at i/ylmdec.i line 357 ```

 lsdir ``` files = lsdir(directory_name) or files = lsdir(directory_name, subdirs) List DIRECTORY_NAME. The return value FILES is an array of strings or nil; the order of the filenames is unspecified; it does not contain "." or ".."; it does not contain the names of subdirectories. If SUBDIRS is given and is a simple variable name, it is set to a list of subdirecotry names (or nil if there are no subdirectories). If DIRECTORY_NAME does not exist, the return value is the integer 0 rather than nil. builtin function, documented at i0/std.i line 1689 ``` SEE ALSO: cd,   mkdir,   rmdir,   get_cwd,   get_home

 lumdist ``` lumdist(z,h0=,k=,lambda0=,Omega_m=,q0=,silent=) See IDL routine... PURPOSE: Calculate luminosity distance (in Mpc) of an object given its redshift EXPLANATION: The luminosity distance in the Friedmann-Robertson-Walker model is taken from Caroll, Press, and Turner (1992, ARAA, 30, 499), p. 511 Uses a closed form (Mattig equation) to compute the distance when the cosmological constant is zero. Otherwise integrates the function using simpson_cosmo. EXAMPLE: Plot the distance of a galaxy in Mpc as a function of redshift out to z = 5.0, assuming the default cosmology (Omega_m=0.3, Lambda = 0.7, H0 = 70 km/s/Mpc) z = span(0,5,50); plg,lumdist(z),z; xytitles,"z","Distance (Mpc)" interpreted function, defined at contrib/cosmo.i line 162 ``` SEE ALSO: ldist