On Wed, 1 Mar 2023 05:28:34 GMT, Joe Darcy <da...@openjdk.org> wrote:
> Last and certainly not least in the port of FDLIBM to Java, the
> transcendental methods for sin, cos, and tan.
>
> Some more tests are to be written in the StrictMath directory to verify that
> the StrictMath algorihtm for sin/cos/tan is being used rather than a
> different one. However, I wanted to get the rest of the change out for review
> first.
>
> The sin/cos/tan methods are grouped together since they share the same
> argument reduction logic. Argument reduction is the process of mapping an
> argument of a function to an argument in a restricted range (and possibly
> returning some function of the reduced argument). For sin, cos, and tan,
> since they are fundamentally periodic with respect to a multiple of pi,
> argument reduction is done to find the remainder of the original argument
> with respect to pi/2.
src/java.base/share/classes/java/lang/FdLibm.java line 519:
> 517: // compute -1.0/(x + r) accurately
> 518: double a,t;
> 519: z = w;
Suggestion:
z = w;
src/java.base/share/classes/java/lang/FdLibm.java line 521:
> 519: z = w;
> 520: z = __LO(z, 0);
> 521: v = r - (z - x); // z + v = r + x
Suggestion:
v = r - (z - x); // z + v = r + x
src/java.base/share/classes/java/lang/FdLibm.java line 524:
> 522: t = a = -1.0/w; // a = -1.0/w
> 523: t = __LO(t, 0);
> 524: s = 1.0 + t*z;
Suggestion:
s = 1.0 + t*z;
src/java.base/share/classes/java/lang/FdLibm.java line 641:
> 639: w = fn*pio2_3;
> 640: r = t - w;
> 641: w = fn*pio2_3t - ((t - r) - w);
let's either align assignments with following `y[0] = r - w;` or remove
redundant space before `=`
src/java.base/share/classes/java/lang/FdLibm.java line 664:
> 662: // set z = scalbn(|x|,ilogb(x)-23)
> 663: z = __LO(z, __LO(x));
> 664: e0 = (ix >> 20) - 1046; /* e0 = ilogb(z)-23; */
Suggestion:
e0 = (ix >> 20) - 1046; /* e0 = ilogb(z)-23; */
-------------
PR: https://git.openjdk.org/jdk/pull/12800
