Add more math fixes

Makefile

@@ -234,7 +234,6 @@ COSMOPOLITAN_OBJECTS =		\
 	LIBC_NT_MSWSOCK		\
 	LIBC_OHMYPLUS		\
 	LIBC_X			\
-	THIRD_PARTY_GDTOA	\
 	THIRD_PARTY_GETOPT	\
 	LIBC_LOG		\
 	LIBC_UNICODE		\
@@ -243,6 +242,7 @@ COSMOPOLITAN_OBJECTS =		\
 	THIRD_PARTY_ZLIB	\
 	THIRD_PARTY_MUSL	\
 	LIBC_STDIO		\
+	THIRD_PARTY_GDTOA	\
 	THIRD_PARTY_REGEX	\
 	LIBC_ALG		\
 	LIBC_MEM		\
@@ -265,8 +265,8 @@ COSMOPOLITAN_OBJECTS =		\
 	LIBC_FMT		\
 	THIRD_PARTY_COMPILER_RT	\
 	LIBC_TINYMATH		\
-	LIBC_SYSV		\
 	LIBC_STR		\
+	LIBC_SYSV		\
 	LIBC_INTRIN		\
 	LIBC_NT_KERNEL32	\
 	LIBC_NEXGEN32E

libc/tinymath/acosf.S

@@ -17,7 +17,6 @@
 │ PERFORMANCE OF THIS SOFTWARE.                                                │
 ╚─────────────────────────────────────────────────────────────────────────────*/
 #include "libc/macros.internal.h"
-.source	__FILE__
 
 //	Returns arc cosine of 𝑥.
 //

libc/tinymath/acosl.S

@@ -17,38 +17,27 @@
 │ PERFORMANCE OF THIS SOFTWARE.                                                │
 ╚─────────────────────────────────────────────────────────────────────────────*/
 #include "libc/macros.internal.h"
-.source	__FILE__
 
 //	Returns arc cosine of 𝑥.
 //
 //	@param	𝑥 is an 80-bit long double passed on stack in 16-bytes
 //	@return	result of computation on FPU stack in %st
-//	@define	atan2(abs(sqrt((1-𝑥)*(1+𝑥))),𝑥)
+//	@define	atan2(fabs(sqrt((1-𝑥)*(1+𝑥))),𝑥)
 //	@domain	-1 ≤ 𝑥 ≤ 1
-//	@mode	long,legacy
+acosl:	pushq	%rbp
-acosl:	push	%rbp
 	mov	%rsp,%rbp
 	.profilable
-	fldl    16(%rbp)
+	fldt	16(%rbp)
-	fld     %st
-#ifdef	__FAST_MATH__
-	fmul	%st(1),%st
-	fsubrs	.Lone(%rip)
-	fsqrt
-#else
 	fld1
-	fsubp
+	fld	%st
-	fld1
+	fsub	%st(2)
-	fadd    %st(2)
+	fxch
+	fadd	%st(2)
 	fmulp
 	fsqrt
-	fabs				# needed in downward rounding mode
+	fabs
-#endif
 	fxch
 	fpatan
-	pop	%rbp
+	leave
 	ret
 	.endfn	acosl,globl
-
-	.rodata.cst4
-.Lone:	.float	1.0

libc/tinymath/asin.S

@@ -17,7 +17,6 @@
 │ PERFORMANCE OF THIS SOFTWARE.                                                │
 ╚─────────────────────────────────────────────────────────────────────────────*/
 #include "libc/macros.internal.h"
-.source	__FILE__
 
 //	Returns arc sine of 𝑥.
 //

libc/tinymath/asinf.S

@@ -17,7 +17,6 @@
 │ PERFORMANCE OF THIS SOFTWARE.                                                │
 ╚─────────────────────────────────────────────────────────────────────────────*/
 #include "libc/macros.internal.h"
-.source	__FILE__
 
 //	Returns arc sine of 𝑥.
 //

libc/tinymath/asinl.S

@@ -17,7 +17,6 @@
 │ PERFORMANCE OF THIS SOFTWARE.                                                │
 ╚─────────────────────────────────────────────────────────────────────────────*/
 #include "libc/macros.internal.h"
-.source	__FILE__
 
 //	Returns arc sine of 𝑥.
 //
@@ -25,27 +24,18 @@
 //	@return	result of computation on FPU stack in %st
 //	@define	atan2(𝑥,sqrt((1-𝑥)*(1+𝑥)))
 //	@domain	-1 ≤ 𝑥 ≤ 1
-//	@mode	long,legacy
+asinl:	pushq	%rbp
-asinl:	push	%rbp
 	mov	%rsp,%rbp
 	.profilable
-	fldl    16(%rbp)
+	fldt	16(%rbp)
-	fld     %st
-#ifdef	__FAST_MATH__
-	fmul	%st(1),%st
-	fsubrs	.Lone(%rip)
-#else
 	fld1
-	fsubp
+	fld	%st
-	fld1
+	fsub	%st(2)
-	fadd    %st(2)
+	fxch
+	fadd	%st(2)
 	fmulp
-#endif
 	fsqrt
-        fpatan
+	fpatan
-	pop	%rbp
+	leave
 	ret
 	.endfn	asinl,globl
-
-	.rodata.cst4
-.Lone:	.float	1.0

libc/tinymath/atan.S

@@ -17,7 +17,6 @@
 │ PERFORMANCE OF THIS SOFTWARE.                                                │
 ╚─────────────────────────────────────────────────────────────────────────────*/
 #include "libc/macros.internal.h"
-.source	__FILE__
 
 //	Returns arc tangent of 𝑥.
 //

libc/tinymath/atanl.S

@@ -17,7 +17,6 @@
 │ PERFORMANCE OF THIS SOFTWARE.                                                │
 ╚─────────────────────────────────────────────────────────────────────────────*/
 #include "libc/macros.internal.h"
-.source	__FILE__
 
 //	Returns arc tangent of 𝑥.
 //

libc/tinymath/pow.S

@@ -17,7 +17,6 @@
 │ PERFORMANCE OF THIS SOFTWARE.                                                │
 ╚─────────────────────────────────────────────────────────────────────────────*/
 #include "libc/macros.internal.h"
-.source	__FILE__
 
 //	Returns 𝑥^𝑦.
 //
@@ -27,4 +26,3 @@
 pow:	ezlea	powl,ax
 	jmp	_d2ld2
 	.endfn	pow,globl
-	.alias	pow,__pow_finite

libc/tinymath/powf.S

@@ -26,4 +26,3 @@
 powf:	ezlea	powl,ax
 	jmp	_f2ld2
 	.endfn	powf,globl
-	.alias	powf,__powf_finite

libc/tinymath/powfin.c

@@ -18,6 +18,13 @@
 ╚─────────────────────────────────────────────────────────────────────────────*/
 #include "libc/math.h"
 
-long double __powl_finite(long double x, long double y) {
+#define powl __powl_finite
-  return powl(x, y);
+#include "libc/tinymath/powl.c"
+
+double __pow_finite(double x, double y) {
+  return __powl_finite(x, y);
+}
+
+float __powf_finite(float x, float y) {
+  return __powl_finite(x, y);
 }

libc/tinymath/scalb.S

@@ -17,7 +17,6 @@
 │ PERFORMANCE OF THIS SOFTWARE.                                                │
 ╚─────────────────────────────────────────────────────────────────────────────*/
 #include "libc/macros.internal.h"
-.source	__FILE__
 
 //	Returns 𝑥 × 2ʸ.
 //

libc/tinymath/sin.S

@@ -17,7 +17,6 @@
 │ PERFORMANCE OF THIS SOFTWARE.                                                │
 ╚─────────────────────────────────────────────────────────────────────────────*/
 #include "libc/macros.internal.h"
-.source	__FILE__
 
 //	Returns sine of 𝑥.
 //

libc/tinymath/sincos.S

@@ -17,7 +17,6 @@
 │ PERFORMANCE OF THIS SOFTWARE.                                                │
 ╚─────────────────────────────────────────────────────────────────────────────*/
 #include "libc/macros.internal.h"
-.source	__FILE__
 
 //	Returns sine and cosine of 𝑥.
 //

libc/tinymath/sincosf.S

@@ -17,7 +17,6 @@
 │ PERFORMANCE OF THIS SOFTWARE.                                                │
 ╚─────────────────────────────────────────────────────────────────────────────*/
 #include "libc/macros.internal.h"
-.source	__FILE__
 
 //	Returns sine and cosine of 𝑥.
 //

libc/tinymath/sincosl.S

@@ -18,7 +18,6 @@
 ╚─────────────────────────────────────────────────────────────────────────────*/
 #include "libc/runtime/pc.internal.h"
 #include "libc/macros.internal.h"
-.source	__FILE__
 
 //	Returns sine and cosine of 𝑥.
 //

libc/tinymath/sinf.S

@@ -17,7 +17,6 @@
 │ PERFORMANCE OF THIS SOFTWARE.                                                │
 ╚─────────────────────────────────────────────────────────────────────────────*/
 #include "libc/macros.internal.h"
-.source	__FILE__
 
 //	Returns sine of 𝑥.
 //

libc/tinymath/tan.S

@@ -17,7 +17,6 @@
 │ PERFORMANCE OF THIS SOFTWARE.                                                │
 ╚─────────────────────────────────────────────────────────────────────────────*/
 #include "libc/macros.internal.h"
-.source	__FILE__
 
 //	Returns tangent of 𝑥.
 //

libc/tinymath/tanl.S

@@ -18,7 +18,6 @@
 ╚─────────────────────────────────────────────────────────────────────────────*/
 #include "libc/runtime/pc.internal.h"
 #include "libc/macros.internal.h"
-.source	__FILE__
 
 //	Returns tangent of 𝑥.
 //

libc/tinymath/tinymath.mk

@@ -40,6 +40,10 @@ $(LIBC_TINYMATH_A).pkg:					\
 		$(LIBC_TINYMATH_A_OBJS)			\
 		$(foreach x,$(LIBC_TINYMATH_A_DIRECTDEPS),$($(x)_A).pkg)
 
+o/$(MODE)/libc/tinymath/powfin.o:			\
+		OVERRIDE_CFLAGS +=			\
+			-ffast-math
+
 LIBC_TINYMATH_LIBS = $(foreach x,$(LIBC_TINYMATH_ARTIFACTS),$($(x)))
 LIBC_TINYMATH_HDRS = $(foreach x,$(LIBC_TINYMATH_ARTIFACTS),$($(x)_HDRS))
 LIBC_TINYMATH_SRCS = $(foreach x,$(LIBC_TINYMATH_ARTIFACTS),$($(x)_SRCS))

test/libc/tinymath/acos_test.c

@@ -0,0 +1,39 @@
+/*-*- mode:c;indent-tabs-mode:nil;c-basic-offset:2;tab-width:8;coding:utf-8 -*-│
+│vi: set net ft=c ts=2 sts=2 sw=2 fenc=utf-8                                :vi│
+╞══════════════════════════════════════════════════════════════════════════════╡
+│ Copyright 2021 Justine Alexandra Roberts Tunney                              │
+│                                                                              │
+│ Permission to use, copy, modify, and/or distribute this software for         │
+│ any purpose with or without fee is hereby granted, provided that the         │
+│ above copyright notice and this permission notice appear in all copies.      │
+│                                                                              │
+│ THE SOFTWARE IS PROVIDED "AS IS" AND THE AUTHOR DISCLAIMS ALL                │
+│ WARRANTIES WITH REGARD TO THIS SOFTWARE INCLUDING ALL IMPLIED                │
+│ WARRANTIES OF MERCHANTABILITY AND FITNESS. IN NO EVENT SHALL THE             │
+│ AUTHOR BE LIABLE FOR ANY SPECIAL, DIRECT, INDIRECT, OR CONSEQUENTIAL         │
+│ DAMAGES OR ANY DAMAGES WHATSOEVER RESULTING FROM LOSS OF USE, DATA OR        │
+│ PROFITS, WHETHER IN AN ACTION OF CONTRACT, NEGLIGENCE OR OTHER               │
+│ TORTIOUS ACTION, ARISING OUT OF OR IN CONNECTION WITH THE USE OR             │
+│ PERFORMANCE OF THIS SOFTWARE.                                                │
+╚─────────────────────────────────────────────────────────────────────────────*/
+#include "libc/math.h"
+#include "libc/runtime/gc.h"
+#include "libc/testlib/testlib.h"
+#include "libc/x/x.h"
+
+TEST(acos, test) {
+  EXPECT_STREQ("1.5707963267949", gc(xasprintf("%.15g", acos(0.))));
+  EXPECT_STREQ("1.5707963267949", gc(xasprintf("%.15g", acos(-0.))));
+  EXPECT_STREQ("1.0471975511966", gc(xasprintf("%.15g", acos(.5))));
+  EXPECT_STREQ("2.0943951023932", gc(xasprintf("%.15g", acos(-.5))));
+  EXPECT_STREQ("0", gc(xasprintf("%.15g", acos(1.))));
+  EXPECT_STREQ("3.14159265358979", gc(xasprintf("%.15g", acos(-1.))));
+  EXPECT_TRUE(isnan(acos(1.5)));
+  EXPECT_TRUE(isnan(acos(-1.5)));
+  EXPECT_TRUE(isnan(acos(NAN)));
+  EXPECT_TRUE(isnan(acos(-NAN)));
+  EXPECT_TRUE(isnan(acos(INFINITY)));
+  EXPECT_TRUE(isnan(acos(-INFINITY)));
+  EXPECT_STREQ("1.5707963267949", gc(xasprintf("%.15g", acos(__DBL_MIN__))));
+  EXPECT_TRUE(isnan(acos(__LDBL_MAX__)));
+}

test/libc/tinymath/asin_test.c

@@ -0,0 +1,40 @@
+/*-*- mode:c;indent-tabs-mode:nil;c-basic-offset:2;tab-width:8;coding:utf-8 -*-│
+│vi: set net ft=c ts=2 sts=2 sw=2 fenc=utf-8                                :vi│
+╞══════════════════════════════════════════════════════════════════════════════╡
+│ Copyright 2021 Justine Alexandra Roberts Tunney                              │
+│                                                                              │
+│ Permission to use, copy, modify, and/or distribute this software for         │
+│ any purpose with or without fee is hereby granted, provided that the         │
+│ above copyright notice and this permission notice appear in all copies.      │
+│                                                                              │
+│ THE SOFTWARE IS PROVIDED "AS IS" AND THE AUTHOR DISCLAIMS ALL                │
+│ WARRANTIES WITH REGARD TO THIS SOFTWARE INCLUDING ALL IMPLIED                │
+│ WARRANTIES OF MERCHANTABILITY AND FITNESS. IN NO EVENT SHALL THE             │
+│ AUTHOR BE LIABLE FOR ANY SPECIAL, DIRECT, INDIRECT, OR CONSEQUENTIAL         │
+│ DAMAGES OR ANY DAMAGES WHATSOEVER RESULTING FROM LOSS OF USE, DATA OR        │
+│ PROFITS, WHETHER IN AN ACTION OF CONTRACT, NEGLIGENCE OR OTHER               │
+│ TORTIOUS ACTION, ARISING OUT OF OR IN CONNECTION WITH THE USE OR             │
+│ PERFORMANCE OF THIS SOFTWARE.                                                │
+╚─────────────────────────────────────────────────────────────────────────────*/
+#include "libc/math.h"
+#include "libc/runtime/gc.h"
+#include "libc/testlib/testlib.h"
+#include "libc/x/x.h"
+
+TEST(asin, test) {
+  EXPECT_STREQ("0", gc(xasprintf("%.15g", asin(0.))));
+  EXPECT_STREQ("-0", gc(xasprintf("%.15g", asin(-0.))));
+  EXPECT_STREQ("0.523598775598299", gc(xasprintf("%.15g", asin(.5))));
+  EXPECT_STREQ("-0.523598775598299", gc(xasprintf("%.15g", asin(-.5))));
+  EXPECT_STREQ("1.5707963267949", gc(xasprintf("%.15g", asin(1.))));
+  EXPECT_STREQ("-1.5707963267949", gc(xasprintf("%.15g", asin(-1.))));
+  EXPECT_TRUE(isnan(asin(1.5)));
+  EXPECT_TRUE(isnan(asin(-1.5)));
+  EXPECT_TRUE(isnan(asin(NAN)));
+  EXPECT_TRUE(isnan(asin(-NAN)));
+  EXPECT_TRUE(isnan(asin(INFINITY)));
+  EXPECT_TRUE(isnan(asin(-INFINITY)));
+  EXPECT_STREQ("2.2250738585072e-308",
+               gc(xasprintf("%.15g", asin(__DBL_MIN__))));
+  EXPECT_TRUE(isnan(asin(__DBL_MAX__)));
+}

test/libc/tinymath/atan_test.c

@@ -0,0 +1,40 @@
+/*-*- mode:c;indent-tabs-mode:nil;c-basic-offset:2;tab-width:8;coding:utf-8 -*-│
+│vi: set net ft=c ts=2 sts=2 sw=2 fenc=utf-8                                :vi│
+╞══════════════════════════════════════════════════════════════════════════════╡
+│ Copyright 2021 Justine Alexandra Roberts Tunney                              │
+│                                                                              │
+│ Permission to use, copy, modify, and/or distribute this software for         │
+│ any purpose with or without fee is hereby granted, provided that the         │
+│ above copyright notice and this permission notice appear in all copies.      │
+│                                                                              │
+│ THE SOFTWARE IS PROVIDED "AS IS" AND THE AUTHOR DISCLAIMS ALL                │
+│ WARRANTIES WITH REGARD TO THIS SOFTWARE INCLUDING ALL IMPLIED                │
+│ WARRANTIES OF MERCHANTABILITY AND FITNESS. IN NO EVENT SHALL THE             │
+│ AUTHOR BE LIABLE FOR ANY SPECIAL, DIRECT, INDIRECT, OR CONSEQUENTIAL         │
+│ DAMAGES OR ANY DAMAGES WHATSOEVER RESULTING FROM LOSS OF USE, DATA OR        │
+│ PROFITS, WHETHER IN AN ACTION OF CONTRACT, NEGLIGENCE OR OTHER               │
+│ TORTIOUS ACTION, ARISING OUT OF OR IN CONNECTION WITH THE USE OR             │
+│ PERFORMANCE OF THIS SOFTWARE.                                                │
+╚─────────────────────────────────────────────────────────────────────────────*/
+#include "libc/math.h"
+#include "libc/runtime/gc.h"
+#include "libc/testlib/testlib.h"
+#include "libc/x/x.h"
+
+TEST(atan, test) {
+  EXPECT_STREQ("0", gc(xasprintf("%.15g", atan(0.))));
+  EXPECT_STREQ("-0", gc(xasprintf("%.15g", atan(-0.))));
+  EXPECT_STREQ("0.463647609000806", gc(xasprintf("%.15g", atan(.5))));
+  EXPECT_STREQ("-0.463647609000806", gc(xasprintf("%.15g", atan(-.5))));
+  EXPECT_STREQ("0.785398163397448", gc(xasprintf("%.15g", atan(1.))));
+  EXPECT_STREQ("-0.785398163397448", gc(xasprintf("%.15g", atan(-1.))));
+  EXPECT_STREQ("0.982793723247329", gc(xasprintf("%.15g", atan(1.5))));
+  EXPECT_STREQ("-0.982793723247329", gc(xasprintf("%.15g", atan(-1.5))));
+  EXPECT_STREQ("nan", gc(xasprintf("%.15g", atan(NAN))));
+  EXPECT_STREQ("-nan", gc(xasprintf("%.15g", atan(-NAN))));
+  EXPECT_STREQ("1.5707963267949", gc(xasprintf("%.15g", atan(INFINITY))));
+  EXPECT_STREQ("-1.5707963267949", gc(xasprintf("%.15g", atan(-INFINITY))));
+  EXPECT_STREQ("2.2250738585072e-308",
+               gc(xasprintf("%.15g", atan(__DBL_MIN__))));
+  EXPECT_STREQ("1.5707963267949", gc(xasprintf("%.15g", atan(__DBL_MAX__))));
+}

test/libc/tinymath/cbrt_test.c

@@ -0,0 +1,41 @@
+/*-*- mode:c;indent-tabs-mode:nil;c-basic-offset:2;tab-width:8;coding:utf-8 -*-│
+│vi: set net ft=c ts=2 sts=2 sw=2 fenc=utf-8                                :vi│
+╞══════════════════════════════════════════════════════════════════════════════╡
+│ Copyright 2021 Justine Alexandra Roberts Tunney                              │
+│                                                                              │
+│ Permission to use, copy, modify, and/or distribute this software for         │
+│ any purpose with or without fee is hereby granted, provided that the         │
+│ above copyright notice and this permission notice appear in all copies.      │
+│                                                                              │
+│ THE SOFTWARE IS PROVIDED "AS IS" AND THE AUTHOR DISCLAIMS ALL                │
+│ WARRANTIES WITH REGARD TO THIS SOFTWARE INCLUDING ALL IMPLIED                │
+│ WARRANTIES OF MERCHANTABILITY AND FITNESS. IN NO EVENT SHALL THE             │
+│ AUTHOR BE LIABLE FOR ANY SPECIAL, DIRECT, INDIRECT, OR CONSEQUENTIAL         │
+│ DAMAGES OR ANY DAMAGES WHATSOEVER RESULTING FROM LOSS OF USE, DATA OR        │
+│ PROFITS, WHETHER IN AN ACTION OF CONTRACT, NEGLIGENCE OR OTHER               │
+│ TORTIOUS ACTION, ARISING OUT OF OR IN CONNECTION WITH THE USE OR             │
+│ PERFORMANCE OF THIS SOFTWARE.                                                │
+╚─────────────────────────────────────────────────────────────────────────────*/
+#include "libc/math.h"
+#include "libc/runtime/gc.h"
+#include "libc/testlib/testlib.h"
+#include "libc/x/x.h"
+
+TEST(cbrt, test) {
+  EXPECT_STREQ("0", gc(xasprintf("%.15g", cbrt(0.))));
+  EXPECT_STREQ("-0", gc(xasprintf("%.15g", cbrt(-0.))));
+  EXPECT_STREQ("0.7937005259841", gc(xasprintf("%.15g", cbrt(.5))));
+  EXPECT_STREQ("-0.7937005259841", gc(xasprintf("%.15g", cbrt(-.5))));
+  EXPECT_STREQ("1", gc(xasprintf("%.15g", cbrt(1.))));
+  EXPECT_STREQ("-1", gc(xasprintf("%.15g", cbrt(-1.))));
+  EXPECT_STREQ("1.14471424255333", gc(xasprintf("%.15g", cbrt(1.5))));
+  EXPECT_STREQ("-1.14471424255333", gc(xasprintf("%.15g", cbrt(-1.5))));
+  EXPECT_STREQ("nan", gc(xasprintf("%.15g", cbrt(NAN))));
+  EXPECT_STREQ("-nan", gc(xasprintf("%.15g", cbrt(-NAN))));
+  EXPECT_STREQ("inf", gc(xasprintf("%.15g", cbrt(INFINITY))));
+  EXPECT_STREQ("-inf", gc(xasprintf("%.15g", cbrt(-INFINITY))));
+  EXPECT_STREQ("2.81264428523626e-103",
+               gc(xasprintf("%.15g", cbrt(__DBL_MIN__))));
+  EXPECT_STREQ("5.64380309412236e+102",
+               gc(xasprintf("%.15g", cbrt(__DBL_MAX__))));
+}

test/libc/tinymath/powl_test.c

@@ -192,7 +192,7 @@ BENCH(powl, bench) {
   double _pow(double, double) asm("pow");
   float _powf(float, float) asm("powf");
   long double _powl(long double, long double) asm("powl");
-  EZBENCH2("pow", donothing, _pow(.7, .2));   /* ~51ns */
+  EZBENCH2("pow", donothing, _pow(.7, .2));   /* ~56ns */
-  EZBENCH2("powf", donothing, _powf(.7, .2)); /* ~52ns */
+  EZBENCH2("powf", donothing, _powf(.7, .2)); /* ~56ns */
-  EZBENCH2("powl", donothing, _powl(.7, .2)); /* ~53ns */
+  EZBENCH2("powl", donothing, _powl(.7, .2)); /* ~56ns */
 }

test/libc/tinymath/tan_test.c

@@ -0,0 +1,41 @@
+/*-*- mode:c;indent-tabs-mode:nil;c-basic-offset:2;tab-width:8;coding:utf-8 -*-│
+│vi: set net ft=c ts=2 sts=2 sw=2 fenc=utf-8                                :vi│
+╞══════════════════════════════════════════════════════════════════════════════╡
+│ Copyright 2021 Justine Alexandra Roberts Tunney                              │
+│                                                                              │
+│ Permission to use, copy, modify, and/or distribute this software for         │
+│ any purpose with or without fee is hereby granted, provided that the         │
+│ above copyright notice and this permission notice appear in all copies.      │
+│                                                                              │
+│ THE SOFTWARE IS PROVIDED "AS IS" AND THE AUTHOR DISCLAIMS ALL                │
+│ WARRANTIES WITH REGARD TO THIS SOFTWARE INCLUDING ALL IMPLIED                │
+│ WARRANTIES OF MERCHANTABILITY AND FITNESS. IN NO EVENT SHALL THE             │
+│ AUTHOR BE LIABLE FOR ANY SPECIAL, DIRECT, INDIRECT, OR CONSEQUENTIAL         │
+│ DAMAGES OR ANY DAMAGES WHATSOEVER RESULTING FROM LOSS OF USE, DATA OR        │
+│ PROFITS, WHETHER IN AN ACTION OF CONTRACT, NEGLIGENCE OR OTHER               │
+│ TORTIOUS ACTION, ARISING OUT OF OR IN CONNECTION WITH THE USE OR             │
+│ PERFORMANCE OF THIS SOFTWARE.                                                │
+╚─────────────────────────────────────────────────────────────────────────────*/
+#include "libc/math.h"
+#include "libc/runtime/gc.h"
+#include "libc/testlib/testlib.h"
+#include "libc/x/x.h"
+
+TEST(tan, test) {
+  EXPECT_STREQ("0", gc(xasprintf("%.15g", tan(0.))));
+  EXPECT_STREQ("-0", gc(xasprintf("%.15g", tan(-0.))));
+  EXPECT_STREQ("0.54630248984379", gc(xasprintf("%.15g", tan(.5))));
+  EXPECT_STREQ("-0.54630248984379", gc(xasprintf("%.15g", tan(-.5))));
+  EXPECT_STREQ("1.5574077246549", gc(xasprintf("%.15g", tan(1.))));
+  EXPECT_STREQ("-1.5574077246549", gc(xasprintf("%.15g", tan(-1.))));
+  EXPECT_STREQ("14.1014199471717", gc(xasprintf("%.15g", tan(1.5))));
+  EXPECT_STREQ("-14.1014199471717", gc(xasprintf("%.15g", tan(-1.5))));
+  EXPECT_STREQ("nan", gc(xasprintf("%.15g", tan(NAN))));
+  EXPECT_STREQ("-nan", gc(xasprintf("%.15g", tan(-NAN))));
+  EXPECT_STREQ("-nan", gc(xasprintf("%.15g", tan(INFINITY))));
+  EXPECT_STREQ("-nan", gc(xasprintf("%.15g", tan(-INFINITY))));
+  EXPECT_STREQ("2.2250738585072e-308",
+               gc(xasprintf("%.15g", tan(__DBL_MIN__))));
+  /* EXPECT_STREQ("-0.0049620158744449",  */
+  /*              gc(xasprintf("%.15g", tan(__DBL_MAX__)))); */
+}