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TRIG.F77
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1985-03-16
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50 lines
* trig test
* 2 2
* calculate sin x + cos x for -90 <= x <= 90
*
* the maximum error is saved and printed after 'iters'
* calculations in real*4 and real*8
program trig test
real*4 x, sx, cx, error, radians
real*8 d x, d sx, d cx, d error, d radians
integer*2 iters
integer*2 max iters
integer*2 i
integer*2 t1 (4), t2 (4)
radians (i) = float (i)*0.01745 32925
d radians (i) = float (i)*0.01745 32925 19943 D 0
write (*, *)' iters: '
read (*, *) max iters
call time (t1)
do 200 iters = 1, max iters
error = 0.0
do 100 i = -90, 90
x = radians (i)
sx = sin (x)
cx = cos (x)
error = max (error, abs (1.0 - sx**2 - cx**2))
100 continue
200 continue
call etime (t2, t1, max iters)
write (*, *)'real*4 error', error
write (*, *)' '
call time (t1)
do 400 iters = 1, max iters
d error = 0.0
do 300 i = -90, 90
d x = d radians (i)
d sx = sin (d x)
d cx = cos (d x)
d error = max (d error, abs (1.0 - d sx**2 - d cx**2))
300 continue
400 continue
call etime (t2, t1, max iters)
write (*, *) 'real*8 error', d error
end